The answer is B. Divergent plate boundary.
Let's look into the choices one by one:
A. Subduction-This is false.
Under subduction force, the subduction plate boundary cause two plates to collide, and thee denser oceanic plate will subduct under the less dense continental plate, causing the plate to be melted in the mantle. As the plate boundary destroy the plate instead of creating new materials, this is false.
B. Divergent-This is correct.
Under the rising convection current of magma, the plates move apart from each other causing crack. The uprising magma would then fill the crack and cools down to form new plate material which adds to the lithosphere.
C. Collisional -This is false.
Collisional and Subduction plate boundary is actually the same,where the plates collide.As mentioned, this does not adds to the lithosphere.
D. Transform- This is false.
Transform plate boundary is where the plates slide past each other and no material is created or destroyed.
Therefore, the answer is B. Divergent plate boundary.
Hope it helps!
