In places where seafloor spreading is occurring, you would expect to see ...

A. a mid-ocean ridge.

B. an oceanic trench.

C. volcanoes.

D. Both A. and C.

The correct answer is D.

Seafloor spreading is a process of creating seafloor crust out of volcanic materials that are emerging from the Earth's core at the mid-ocean ridges.

This is made possible by the moving of Earth's tectonic plates.