Which statements are true?

A.
L2TPv2 can run over UDP or directly over IP.

B.
L2TPv2 can run over UDP only.

C.
L2TPv3 can run over UDP or directly over IP.

D.
L2TPv3 can run over UDP only.

E.
L2TPv2 and L2TPv3 always use TCP as reliable transport.