Hello there! The answer is c. 15!
Basically, the question is asking you, what can you multiply 8 by to get the same result as when you multiply 8 by 15?
Knowing this, you can come to the quick conclusion that the answer is 15, since you are multiplying 8 by the same number in both cases, meaning you will get the same result!
I hope this helps and have a great day!