when we multiply a number by its "Multiplicative Inverse" we get 1.
Therefor the Multiplicative inverse of (-3/7)to the power of -5 is
a) (-3/7)to the power of 5
As (-3/7)^(-5) = (-7/3)^5
When we multiply (-7/3)^5 with (-3/7)^5 we get 1 hence a) (-3/7)^5