If f(x) = 6x3 + 5x, g(x) = 3x2 + 5, and h(x) = 9x2 – 8, what is the degree of f(g(h(x)))?

The degree of h(x) = 9x² − 8 is 2. Substituting h(x) into g, which has degree 2, gives g(h(x)) a degree of 2 × 2 = 4. Then f has degree 3, so f(g(h(x))) has degree 3 × 4 = 12. The correct choice is D, 12.

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