Answer:
A. $30,000
Explanation:
To solve this you just have to do a simple rule of three, where in one side has the price of the car that his parents bought for 8,000 dollars and calculate the money that colin´s car costed in the other side:

So now we know that the car that Colin bought was 3.75 times as expensive as his parents 8,000 dollar car, that means it costed 30,000 dollars.