$$7^{6n} - 6^{6n}$$, where n is an integer > 0, is divisible by
Consider n=1 we have $$7^{6} - 6^{6}$$ which is = $$(7^{3} + 6^{3})(7^{3} - 6^{3})$$ = 13 * 127 * 43 which is divisible by all the 3 options.
Option d) is the correct answer.
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