I’m having slot of trouble with this question, can anyone help?

Answer:
B.
Step-by-step explanation:
"f of g of x" is the pronunciation of that and essentially represents putting the entire g(x) function into the "x" of the f(x) function.
Looking at your choices, B. looks to fit that description.
g(x)=(x-9)/(x+4) and if you put that into f(x)=(x)^1/3, you'll get h(x).