Analyze the map below and answer the question that follows.

A satellite map of Southeast Asia. Bodies of water on the map are labeled A, B, C, and D. A is between Cambodia and Malaysia. B is between Vietnam and China. C is between Vietnam and the Philippines. D is the Pacific Ocean.
Image courtesy of NASA

Each of the letters on the map above marks a body of water in Southeast Asia. Which two letters represent gulfs?
A.
A and B
B.
B and C
C.
C and D
D.
A and C