Answer: B. 8n^18
Explanation:
From the question, we are informed that the area of a square is 64n^36. The length of one side of the square would be calculated as the square root of the value given. This will be:
= ✓64n^36
= ✓64 × ✓n^36
= 8 × (n^36 × 1/2)
= 8 × n^18
= 8n^18
Therefore, the correct option is B.