Answer: (6^-8/7^-12)
Explanation:
In this type of problems, you apply the laws of indices which stated that
( a²/b²)³ =( a²×³/b²×³)
= ( a6/b6)
From this question now, applying the above principle
(6²/7³)-4
= (6²×-⁴/7³×-⁴)
= (6^-8/7^-12)
So the answer is C