Answer: Choice B

======================================================
Step-by-step explanation:
The two rules we use are


When applying the first rule to the expression your teacher gave you, we can say that:

Then applying the second rule lets us say

Therefore,

-------------
In short, we just multiplied each exponent inside by the outer exponent 1/2.
So that explains why the exponents go from {1/4,16} to {1/8,8} for x and y in that exact order.