When two plates carrying oceanic crust collide, the heavier plate will dive under the lighter plate and sink into the upper mantle in a process called

A. subduction.

B. plate tectonics.

C. folding.

D. convergence.

When two plates carrying oceanic crust collide, the heavier plate will dive under the lighter plate and sink into the upper mantle in a process called "subduction," since the "sub" part of the word means "under".