Explanation:
the second option 1/(125n¹²)
why ?
when we have the exponent of an exponent, we can multiply the exponents.
so, 4×-3 = -12
a negative exponent means 1/... (with the corresponding positive exponent in the denominator).
and an exponent of the multiplication of factors means that the exponent is to be used for every factor in the multiplication.
so, the exponent -3 has to be applied to 5 and to n⁴.
this gives us 5^‐3 and n^-12 as factors.
the result is 1/(5³) × 1/(n¹²).
and that is the mentioned result above.