What forms when one oceanic plate is forced beneath another plate?

A. an ocean basin

B. ocean ridges

C. a subduction zone

D. a rift valley

What forms when one oceanic plate is forced beneath another plate is C. a subduction zone.

The name itself can explain it all - the prefix sub - in Latin means 'under,' and given that beneath and under mean the same, subduction zone is the answer you should pick. The other options do not show such a relationship which is why they are wrong.