To determine if $x - 5$ is a factor of the polynomial function $f(x) = x^3 - 125$ using the Factor Theorem, evaluate the function at the corresponding value of $c$. For the binomial $x - 5$, the value is $c = 5$. Substitute $x = 5$ into the function: $f(5) = 5^3 - 125$. Evaluate the exponent to obtain $f(5) = 125 - 125$, which simplifies to $f(5) = 0$. Because the function evaluates to $0$, the Factor Theorem confirms that $x - 5$ is a factor of $f(x) = x^3 - 125$.