Question

according to the theory of seafloor spreading, what causes changes in the sea floor?
water movement
fish populations
volcanic activity at the mid - ocean ridge
sedimentary activity at the mid - ocean ridge

Explanation:

The theory of seafloor spreading posits that new oceanic crust is formed through volcanic activity at mid - ocean ridges. Magma rises up from the mantle at these ridges, cools, and solidifies to form new crust, pushing the existing crust away from the ridge and causing changes in the sea floor. Water movement, fish populations, and sedimentary activity at mid - ocean ridges are not the main causes of sea - floor changes according to this theory.

Answer:

C. volcanic activity at the mid - ocean ridge