On January 1, 2016, Finnegans, Inc. purchased equipment having an estimated useful life of 10 years. Resale value at the end of its service was estimated at 20% of original cost. On December 31, 2020, the equipment was sold for 50% of its original cost. Finnegans recognized a loss on the sale. Which of the following depreciation methods had Finnegans been using?

Select one:

a. Straight-line

b. Sum-of-the-years-digits

c. Double-declining balance

d. Either A or B

e. Either B or C

f. Either A, B, or C