Nowland Woodworks purchased a truck at a cost of $12,000. The truck has a residual value of $2,000 and an estimated useful life of 5 years or 10,000 hours of estimated use. The truck was purchased on January 1, 2019, and was used 2,700 hours in 2019 and 2,600 hours in 2020. If the company uses the straight line method of depreciation, what is the book value of the truck at December 31, 2021? A. $6,000 B. $10,000 C. $8,000 D. $4,000