The most prominent feature of ocean topography discovered in the 1960s was:

1) volcanic activity at the ocean bottom
2) a submerged mountain ridge
3) seamounts
4) subduction zones

Volcanic

The most prominent feature of ocean topography discovered in the 1960s was: Volcanic activity at the ocean bottom. The continents have always been in their current positions.

hope it helps :)

the answer is c. according to past decisions, free speech is not unlimited.