(a) Depreciation is a method of allocating the cost of an
asset in a systematic and rational manner. Since the units-of production
method of depreciation is most appropriate when
depreciation is a function of activity, answer (a) is correct. Answer
(b) is incorrect because this situation warrants the use of a
depreciation method based on the passage of time. Answers (c)
and (d) are incorrect because both support the use of an accelerated
method of depreciation.