Answer: A. accumulation; ablation
Explanation:
A Glacier is an ice mass that moves from the sheer force of its own weight. Glaciers are formed when ice is accumulated faster than the rate at which it melts. With increasing temperatures worldwide,especially in locations where glaciers occur, the reverse is now true, with the rate of  accumulation being less than the rate of ablation.
Ablation is the term used to describe the melting of glaciers.
