Final answer:
To find the geometric mean of 8 and 12, the problem should be set up as the square root of their product, represented by option A: √(8 * 12).
Step-by-step explanation:
If a question asks to find the geometric mean of 8 and 12, you would set up the problem as the square root of the product of the two numbers. The correct choice from the options provided is A. √(8 * 12). This computation stems from the definition of geometric mean for two numbers, which is the square root of their product. Therefore, calculating the geometric mean involves multiplying 8 by 12, and then taking the square root of the resulting number.