A motorcycle is depreciating at 19% per year, every year. A student's $21,000 motorcycle depreciating at this rate can be modeled by the equation V(t) =

A motorcycle is depreciating at 19% per year, every year. A student's $21,000 motorcycle depreciating at this rate can be modeled by the equation V(t) = 21,000(0.81)^t. What is an equivalent equation for this vehicle as a monthly depreciation and, using this equation, what is the motorcycle worth (rounded to the nearest ten dollar) 4 years after purchase?

A. V(t) = 21,000(1.19)−t, $10,470 

B. V(t) = 21,000(0.8100)12t, $19,580

C. V(t) = 21,000(0.9826)12t, $9,040

D. V(t) = 21,000(0.9826)t, $9,040