OSPF does not use TCP or UDP because it has its own reliable transmission mechanisms.

OSPF packets are encapsulated directly in IP packets using protocol number 89.

TCP (A) is used for connection-oriented communication, but OSPF does not rely on it.

UDP (C) is used for connectionless communication, but OSPF does not use it.

HTTP (B) is an application-layer protocol and irrelevant here.

Thus, the correct answer is D (IP).