Diverse paths are network connections that use different physical routes or mediums to reach the same destination12.
Diverse paths provide redundancy and fault tolerance in case of a network failure or outage, as traffic can be rerouted to an alternative path12.
In this scenario, the company has a secondary connection to the same ISP, but it uses a different path than the primary connection, which is experiencing an outage12.
Therefore, the traffic can continue to flow through the secondary connection, which is a diverse path12.
Load balancing is a technique that distributes network traffic across multiple servers or links to optimize performance and availability12. Load balancing does not necessarily imply diverse paths, as the traffic may use the same or similar routes to reach the destination12.
Multipathing is a technique that allows a device to use more than one path to communicate with another device, such as a server or a storage array12. Multipathing can improve performance, reliability, and load balancing, but it is not the same as diverse paths, as the paths may share some common segments or components12.
Virtual Router Redundancy Protocol (VRRP) is a protocol that allows multiple routers to act as a single virtual router for a group of hosts on a network segment12. VRRP provides redundancy and failover for the default gateway, but it does not describe the configuration of the network connections between the routers and the ISP12. Reference:
1: CompTIA Network+ N10-008 Exam Cram, 6th Edition, Chapter 2: Network Design and Implementation, p. 59-60
2: CompTIA Network+ N10-008 Cert Guide, 1st Edition, Chapter 3: Network Design, p. 97-98

Split tunnel is a configuration that allows a remote user to access both the local network and the Internet at the same time. In a split tunnel configuration, only traffic destined for the corporate network is sent through the VPN tunnel, while all other traffic is sent directly to the Internet. This allows the remote user to access the Internet without the company's VPN server being able to monitor or intercept their traffic. Using a split tunnel configuration can help the company to mitigate employee concerns about internet activity being monitored and reassure employees that their private internet activity is not being monitored.

172.19.0.2 is a valid IP address configuration for the device that uses a static RFC1918 address for the network and allows for a connection over NAT (Network Address Translation). RFC1918 addresses are private IP addresses that are not routable on the public Internet and are used for internal networks. The RFC1918 address ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. NAT is a technique that translates private IP addresses to public IP addresses when communicating with external networks, such as the Internet. FE80::1 is an IPv6 link-local address that is not a static RFC1918 address and does not allow for a connection over NAT. 100.64.0.1 is an IPv4 address that belongs to the shared address space range (100.64.0.0/10) that is used for carrier-grade NAT (CGN) between service providers and subscribers, which is not a static RFC1918 address and does not allow for a connection over NAT. 169.254.1.2 is an IPv4 link-local address that is automatically assigned by a device when it cannot obtain an IP address from a DHCP server or manual configuration, which is not a static RFC1918 address and does not allow for a connection over NAT. 224.0.0.12 is an IPv4 multicast address that is used for VRRP (Virtual Router Redundancy Protocol), which is not a static RFC1918 address and does not allow for a connection over NAT.

A proxy server is an intermediary server that acts as a gateway between the internet and the users. It has its own IP address, so the internet activities appear to be coming from the proxy server instead of the users' devices1.
A proxy server can provide several benefits, such as caching web pages, filtering content, bypassing geo-restrictions, and enhancing privacy and security1.
A proxy server can be configured to allow or deny access to certain websites or protocols based on the corporate network policy1.
A VPN client is a software application that creates an encrypted tunnel between the user's device and a VPN server. A VPN client can also change the user's IP address, but it does so for the entire operating system, not just for specific applications2.
A VPN client can provide more security and privacy than a proxy server, but it also requires more resources and may slow down the internet connection2.
A VPN client is usually used to access remote networks or bypass censorship, not to comply with corporate network policy2.
A bridge is a network device that connects two or more network segments and forwards data frames based on their MAC addresses3.
A bridge can increase the performance and security of a network by reducing collisions and filtering traffic3.
A bridge does not change the IP address of the users or the network segments, nor does it provide any gateway function to the internet3.
A bridge is usually used to extend or segment a local area network (LAN), not to connect to the internet3.
A VLAN is a logical grouping of network devices that share the same broadcast domain, regardless of their physical location or connection.
A VLAN can improve the performance, security, and management of a network by reducing broadcast traffic, isolating network segments, and enforcing access control policies.
A VLAN does not change the IP address of the users or the network devices, nor does it provide any gateway function to the internet.
A VLAN is usually used to create subnetworks within a LAN, not to connect to the internet.
Reference:
Proxy vs. VPN: What Is the Difference? | Fortinet
What's the difference between a proxy server and a VPN? | Windows Central Bridge (networking) - Wikipedia
[VLAN (Virtual Local Area Network) - Definition from Techopedia]

To identify the source and destination addresses of the traffic causing network saturation, the network administrator should use a network protocol analyzer that supports the NetFlow protocol. NetFlow is a network protocol that collects IP traffic information as it enters or exits an interface and sends it to a NetFlow collector for analysis. This data includes the source and destination addresses of the traffic, the ports used, and the number of bytes and packets transferred.
Therefore, the correct answer is option D, NetFlow.