Question

how do you avoid paying interest on your credit card (or any other loan for that matter)?
always make the minimum payment on time
pay interest 1st, then pay what you can on leftover balance
always make the full payment on time
pay the principal 1st, then pay what you can on interest

Explanation:

To avoid paying interest on a credit card or loan, paying the full balance on time is key. Minimum payments or partial payments (with interest - first or principal - first approaches that leave a balance) will result in interest charges on the remaining balance. Making the full payment on time means there's no balance left for interest to accrue on.

Answer:

Always make the full payment on time (the option in the orange box)