A fair die is tossed eight times. The probability that a third six is observed on the eight throw is

Question

$\begin {array} {1 1} (A)\;\large\frac{7C_2 \times 5^5}{6^7} & \quad (B)\;\large\frac{7C_2 \times 5^5}{6^8} \\ (C)\;\large\frac{7C_2 \times 5^5}{6^6} & \quad (D)\;None\: of \: these \end {array}$