Determine the option that is the least expensive for buying a car.
A.paying $21,000 cash
B.making a $5,000 down payment for a $20,000 installment loan with an APR of 4% over 36 months
C.making a $10,000 down payment for a $20,000 installment loan with APR of 2% over 48 months
D.making no payment for a $20,000 installment loan with APR of 1% over 60 months​