The given expression is:

The index 5 indicates that this term is multiplied by itself 5 times:
(6*3)(6*3)(6*3)(6*3)(6*3)
According to the laws of exponents, if you raise to a certain power a term on parentheses, you can distribute said exponent to each term inside the parentheses, symbolically:

Considering this you can rewrite the given exponent as:

So the equivalent expression is C.