In the equation \( x^8 = 3(x + 4)^2 \), we want to identify which expression represents a product.
The expression \( 3(x + 4)^2 \) features the number 3 multiplied by the square of the binomial \( (x + 4) \). This indicates a product because it can be rewritten in terms of multiplication as \( 3 \times (x + 4)(x + 4) \).
So the correct answer is:
3(x + 4)^2