C ; The are most active at temperatures about 53 degrees
Because there will eventual reach a point where the food or some other necessity runs out and instead of growth continuing, it stays at relatively constant.
The answer for your question is preganent
Because it causes them to move, and so they weather that way. Buut the acid rain can leak into the rock and slowly break down the atoms, causing it to chemically weather faster. Also, just regular water/rain can wash away some covering sediment.
