Jimmy bought a car yesterday,but it's_____used one

问题描述:

Jimmy bought a car yesterday,but it's_____used one
A.a
C.the
为啥选A不选C,the used one为啥不对

a 泛指,the 特指,他买了辆车,但是是一辆旧的.而不是说是这两旧的.