76n- 66n, where n is an integer >0, is divisible by

Answer: Option D

$$\begin{array}{rl}& 7^{6n}-6^{6n}\\ & =7^6-6^6\\ & ={\left(7^3\right)}^2-{\left(6^3\right)}^2\\ & =\left(7^3-6^3\right)\left(7^3+6^3\right)\\ & =\left(343-216\right)\times \left(343+216\right)\\ & =127\times 559\\ & =127\times 13\times 43\end{array}$$
Clearly, it is divisible by 127, 13 as well as 559