Answer:
(d) 6
Explanation:
The degree of a composition of polynomials is the product of the degrees of the contributing functions.
__
f(g(h(x))) = -(3(2x+5)² -1)³
f(g(h(x))) = -1728x⁶ -25920x⁵ -161568x⁴ -535680x³ -996336x² -985680x -405224
The degree of (f∘g∘h)(x) is 6.
_____
3×2×1 = 6