Subnet Mask separates the part host and part subnet on the IP address.

Explanation
1 - E, 2 - B, 3 - D, 4 - A

Reference: https://developer.cisco.com/

A firewall is a network device that monitors incoming and outgoing traffic and decides whether to allow or block specific traffic based on a defined set of rules.
* Function of a Firewall:
* Traffic Monitoring: It continuously monitors all traffic passing through it.
* Rule-Based Filtering: It applies predefined security rules to allow or deny traffic.
* Protection: It protects networks from unauthorized access and cyber threats.
* Comparison with Other Devices:
* Switch: A network device that connects devices within a LAN and uses MAC addresses to forward data to the correct destination.
* Load Balancer: Distributes network or application traffic across multiple servers to ensure no single server becomes overwhelmed.
* Reverse Proxy: A server that sits in front of web servers and forwards client requests to those web servers.
Therefore, a firewall is the correct answer because it specifically monitors and filters network traffic based on security rules.
References:
* Cisco Firewalls Overview: Cisco Firewall Products

Basic authentication uses Base64 converting the string 'username:password'.
Bearer <token here> is for OAuth
https://developer.cisco.com/docs/epnm/#!how-to-authenticate/authorization