20. Vickers Company uses the units-of-activity method in computing depreciation. A new plant asset is purchased for $18,000 that will produce an estimated 100,000 units over its useful life. Estimated salvage value at the end of its useful life is $2,000. What is the depreciation cost per unit? a. $1.60 b. $1.80 c. $0.16 d. $0.18