S purchased equipment for $80,000 on 1 July year 1. The companys accounting year end is 31 December. It is Ss policy to charge a full years depreciation in the year of purchase. S depreciates its equipment on the reducing balance basis at 25% per annum. What is the net book value of the equipment at 31 December year 4?

A. Nil B. $25,312 C. $29,531 D. $33,750