Final answer:
The activity method of depreciation is a variable charge approach that associates cost with input measures, not the passage of time.
Step-by-step explanation:
The activity method of depreciation is considered a variable charge approach to depreciation. This method does not assume that depreciation is a function of the passage of time. Instead, it conceptually associates cost with input measures, such as the number of hours a piece of machinery is used or the number of units it produces. Due to this, the most accurate option would be that the activity method of depreciation is a variable charge approach.