The apportionment of the cost of equipment to future periods under the matching principle is

A) depletion.
B) amortization.
C) depreciation.
D) allocation.

The apportionment of the cost of equipment to future periods under the matching principle is depreciation. Depreciation recognizes the use of assets over their useful lives, and allocates the cost of the asset over those periods. Therefore, option C is the correct choice. Option A (depletion) is used for natural resources, option B (amortization) is used for intangible assets, and option D (allocation) is a general term for the distribution of costs across periods or accounts.