two oceanic plates converging two continental plates converging two continental plates diverging two oceanic plates diverging
I gave my students this multiple choice question: Which of these explains how a trench can form?

Only one answer is correct among these 4 choices:
- two oceanic plates converging
- two continental plates converging
- two continental plates diverging
- two oceanic plates diverging

Could you tell me which one is correct?

two oceanic plates converging