This question has been answered but I'm looking for clarification on something I'm struggling to understand

Here's the question

You want to buy a new car which costs $25,000. You have the following two alternatives for financing the purchase:

Alternative A: If you buy the car in cash from the dealer, you will receive an instant cash rebate of $1,000. Your parents are willing to lend you the cash at a rate of 5% over 2 years with quarterly repayments.

Alternative B: Buy the car for $25,000 with a 4% bank loan over 2 years with quarterly repayments. Which alternative do you prefer?

Here's the answer with an explanation.

What I don't quite understand is why are we trying to figure out the payment and using that as our reference to find our preferred option?

We already have our present value of both the answers. Why do the payments matter if we know what the value of them will be? I really hope that I'm not missing something here.

Thank you.

Alternative A: PV $24,000 i 5% / 4 = 1.25% 2 years x 4 8 PMT ? [1 - (10.0125) 24,000 = PMT 0.0125 = $3,171.20 n = Preferred alternative Alternative B: PV $25,000 1 (1 0.01)-8' 25,000 PMT 0.01 i 4% / 4 = 1% = $ 3,267.26 n 2 years x 4 = 8 PMT