The following description about BGP, OSPF, ISIS, which the description is true?

The following description about BGP, OSPF, ISIS, which the description is true?
A . BGP neighbor relationship is established based on TCP session, and the port number used is 179
B . ISIS runs based on IP protocol, the protocol number adopted is 89
C . BGP runs based on UDP sessions, and the port number used is 179
D . OSPF runs based on IP protocol, the protocol number adopted is 90

Answer: A