The correct answer is User Datagram Protocol.

The User Datagram Protocol operates at the transport layer because it provides end to end multiplexing with port numbers and it offers an unreliable datagram service on top of the Internet Protocol. It is assigned IP protocol number 17 and it relies on IP for addressing and routing so it sits above the Internet layer.

Internet Group Management Protocol is incorrect because it is an Internet layer protocol used to manage IPv4 multicast group membership and it is carried directly by IP rather than providing transport services.

Internet Control Message Protocol is incorrect because it provides diagnostic and control messages for IP such as echo request and destination unreachable and it is implemented as part of the Internet layer rather than the transport layer.

Internet Protocol is incorrect because it is the core Internet layer protocol that handles packet addressing and routing and transport protocols like UDP and TCP run on top of it.

Full AWS Practitioner Certification Question