Answer:
C
Explanation:
What you wrote is not the same thing as what the question is, or at least I don't think so. I'll answer the printed question.
First of all, the 13 is what separates each of the terms. In other words 7 is the first term. 13 must be raised to the n - 1 power.
It is written like this
an = 7 * 13^(n - 1)
you want a1 to be 7. The only way that can happen is if 13^0 which gives you 1.
So the correct answer is C