The IP source guard is enabled.
The configuration shows that ip-source-guardis explicitly enabled under dhcp-security.
Dynamic ARP inspection is enabled.
The configuration also includes arp-inspectionunder dhcp-security, which indicates that Dynamic ARP Inspection (DAI) is enabled.
DHCP snooping is enabled.
DHCP snooping is implied as enabled because both IP source guard and ARP inspection are dependent on the DHCP snooping database to function properly. Even though DHCP snooping is not explicitly mentioned, its presence is required for these features to work.

The feature that enables an interface on an EX Series switch to receive both untagged traffic (from the computer) and tagged traffic (from the IP phone) is the voice VLAN. The voice VLAN feature in EX-series switches enables access ports to accept both data (untagged) and voice (tagged) traffic and separate that traffic into different VLANs. This allows the switch to differentiate between voice and data traffic, ensuring that voice traffic can be treated with a higher priority.

Both aggregate and generated routes would work, but the best choice is generated routes.
One key difference:
With aggregated routes any prefix in the routing table counts as a contributing route.
With generated routes only prefix with a valid next-hop qualifies.

A is correct because the interface is configured as a disabled port. A disabled port does not forward any traffic, including DHCP packets. Therefore, DHCP snooping cannot learn any MAC addresses or lease information from a disabled port.
C is correct because the interface is configured as a trunk port. By default, all trunk ports on the switch are trusted for DHCP snooping. This means that DHCP snooping does not inspect or filter any DHCP packets received on a trunk port. Therefore, DHCP snooping does not add any entries to the snooping database for a trunk port.

A) On R1, enable Level 1 on the ge-0/0/1 interface. In IS-IS, both levels (Level 1 and Level 2) are enabled by default when you enable IS-IS on an interface1. Level 1 systems route within an area.
If the destination is outside an area, Level 1 systems route toward a Level 2 system. Therefore, enabling Level 1 on the ge-0/0/1 interface on R1 would allow packets to reach from R1 to R3.
D) On R3 enable Level 1 on the ge-0/0/4 interface Similarly, enabling Level 1 on the ge-0/0/4 interface on R3 would allow packets to reach from R1 to R3. These explanations are based on the IS-IS configuration documents and learning resources available at Juniper Networks1 and Cisco.