The answer is B. The theory of isostatic equilibrium is used to explain the vertical height of a particular point on the earth such as the Himalayas. This theory is very similar to the principle of buoyancy. The mantle, in this case, is the liquid being displaced by the crust above. To accommodate great pressures such as those exerted by the Himalayas, the mantle distributes the force by height adjustments.
The movement of the sand parallel to the shore is call long shore drift I learned this in school but if I got it wrong I’m so sorry but it’s good enough that I tried to do it and help you
The two most obvious ones are on the far right, and near the far left. Oceanic lithosphere is descending into the earth's mantle at these places, and being destroyed. ... At convergent boundaries oceanic lithosphere is always destroyed by descending into a subduction zone
