If x is a positive integer, which of the following must be true about 3^(2x) - 1?

✓ Correct Answer: Option D

3^(2x) - 1 = (3^x)^2 - 1 = (3^x - 1)(3^x + 1). Since 3^x is always odd, both (3^x - 1) and (3^x + 1) are consecutive even integers. One of them must be divisible by 4, and the other by 2. Therefore, their product is always divisible by 8.