Divergent boundaries are defined by?

• A. Two plates collide.
• B. Two plates slide past each other.
• C. One plate sinks beneath another.
• D. Two plates spread apart.

Answer: (D)

Divergent boundaries are defined by the plates moving away from each other. When they pull apart, mantle material rises to fill the gap and soon cools to form new crust. On the ocean floor this process creates mid-ocean ridges and drives seafloor spreading; on land it can create rift valleys. This spreading apart is the hallmark that distinguishes divergent boundaries from other boundary types, which involve plates colliding, sliding past one another, or one plate being forced beneath another.