Ocean trenches form over millions or billions of years. which statement accurately

Ocean trenches form over millions or billions of years. which statement accurately describes how ocean trenches form?

a )a plate of oceanic crust is subducted under a plate of continental crust
b) two plates of continental crust slide past each other
c) two plates of oceanic crust pull away from each other
d) a plate of continental crust collides with another plate of continental crust