Divergent plate boundaries occur where hot magma rises to the surface, pushing the plates apart. the mid-ocean ridges, as seen here, form at divergent plate boundaries. the older crust in this case would be at point d, the news at point a. what type of rock would you expect to find forming at point a?

Majorly, Extrusive igneous rocks

Explanation:

I uploaded 3 pictures to describe how divergence occur between tectonic plates.

Divergence boundary usually occur between continental plates or oceanic plates.  Base on the question, it occurred between oceanic plates. The oceanic plates move apart  causing an uprising of molten magma to the earth surface. The up welling of this magma usually occur at the mid oceanic ridges . The magma may erupt or/and squeezed out through fissures or cracks . The resulting magma solidifies to form new crust at the surface.  From the third picture you could notice the rocks form closer to the mid oceanic ridge is usually younger and can be denoted as point A. As one move further away from the mid oceanic ridge the rocks becomes older . Rocks found farther away from the mid oceanic ridge can be denoted as point D.

The rocks most likely formed from this kind of boundary is known as extrusive igneous rocks. Generally, igneous rocks are formed from molten magma but the environment of solidification determines the kind of igneous rocks formed. The Extrusive igneous rocks are formed when this magma rises to the earth surface and solidified . The solidification of this magma at the earth surface results to extrusive igneous rocks. The major type of rocks formed on the ocean floor is basalt. The Basaltic nature of the oceanic crust contributes to it high density nature. Basaltic rocks are extrusive igneous rocks.