If the integers m and n are chosen at random between 1 and 100, then the probability that a number of the form $7^m+7^n$ is divisible by 5 equals.

Question

$\begin {array} {1 1} (A)\;\large\frac{1}{4} & \quad (B)\;\large\frac{1}{7} \\ (C)\;\large\frac{1}{8} & \quad (D)\;\large\frac{1}{49} \end {array}$