Bo has $500 in his savings account. He plans to add $150 to his savings account every month. Recently, he purchased a tractor to use on his farm for $4,000. He plans to pay off the total price of the tractor over time by paying $200 a month from a separate account. How much will Bo have in his savings at the time he pays off the tractor in full? A. $3,500 B. $3,000 C. $2,150 D. $2,000.