the answer is the third one; one over five to the sixth power
explained: when multiplying exponents, you use addition to help you. (5 x 5 to the fourth)second power; you would add the exponent of the number in the parentheses together (1 and 4) to get 5. once you do that, you multiply the exponent of 5 by the exponent of 2 (since 2 is outside the parentheses) now you have 5 to the fourth on top of the fraction, and 5 to the tenth in the denominator. To divide your exponents, you use subtraction. Since the denominator’s exponent is larger than the the numerator’s exponent, you subtract 4 from 10 and get 5 to the sixth power in the denominator. stick a one in the numerator and then you’re all done!
Hope this helped