Look at the dictionary definition of the word subterranean.
subterranean \ ˌsəb-tə-ˈrā-nē-ən \ adjective: underground
Which sentence best uses the word subterranean?
(A) The group is planning on going on a subterranean dive in the ocean.
(B) The subterranean building had a view of the mountains around it.
(C) The trees' leaves have fallen in the subterranean area around them.
(D) The prairie dogs lay snug in their subterranean den throughout the winter.