The equation is expressed as
x = log5 125
We would express 125 as 5^3
Thus, the equation would be
x = log5 5^3
We would apply one of the laws of logarithm which is expressed as
logb M^k = klogb M
The expression becomes
x = 3log5 5
We would apply another law which is expressed as
logb b = 1
b in this case is 5
Thus, we have
x = 3 * 1
x = 3
The correct option is b