The older crust in this case would be at point D, the newest at point A. what type of rock would you expect to forming at point A?

Explanation:

New ocean crust is formed at the mid ocean ridges. The new crust is then pushed away from the ridge as newer crust comes to the surface. The ocean crust then spreads out enlarging the ocean. The farer away from the ridge the ocean crust is the older the crust

b) the inside picture would look at a very high temperature in a very low ph