Which two statements about the IPv4 TTL field are true?

Which two statements about the IPv4 TTL field are true? (Choose two.)

A.
If the TTL is 0, the datagram is automatically retransmitted.

B.
Each router that forwards an IP datagram reduces the TTL value by one.

C.
It is used to limit the lifetime of an IP datagram on the Internet.

D.
It is used to track IP datagrams on the Internet.