Final answer:
The grace period for certificate renewal is 30 days and the late fee applied after that is $50.
Step-by-step explanation:
The correct answer to the question is option b) 30, 50.
This information is related to credit card payments where a late fee of $10 is charged and there is a grace period of 30 days for certificate renewal. After the grace period, an additional fee of $5 per day is charged for each day the payment remains unpaid.
Therefore, the answer is b) 30, 50.