What would happen if the rate of seafloor spreading was faster than the rate of subduction? Arc volcanoes would not form. The ocean basins would shrink. The Earth would become smaller. The Earth would grow larger.

Option (D)

Explanation:

The seafloor spreading refer to the condition where the lithospheric plates move away from one another. This results in the addition of new materials along the mid oceanic ridge. If this continues at a greater rate in comparison to the rate of subduction then it results in the expansion of the earth's surface, making the earth grow larger.

But in nature, this rate of spreading is balanced by the rate of subduction. This is how the plate motion works on earth.

Thus, the correct answer is option (D).