Answer:
Loan A is the cheapest.
Explanation:
The different loan plans are showed in the image attached.
Loan A: 12 months of duration with 9.50%.
Loan B: 24 months of duration with 8.75%.
Loan C: 36 months of duration with 7.75%.
Loan D: 48 months of duration with 6.60%.
Now, all loans are compouneded monthly. Let's the compound interest formula

Loan A:

Loan B:

Loan C:

Loan D:

Now, if you compare, you will observe that Loan A offer the cheapest result for Judy.
Therefore, Judy should use the Loan A plan.