If f(x) = 3x - 1 and g(x) = x² - 4, what is g(f(2))?

The notation $g(f(2))$ means apply $f$ first. $f(2)=3(2)-1=5$. Then $g(5)=5^2-4=21$, choice J. Choice F ($5$) stops after the inner function and reports $f(2)$. Choice G ($0$) is $g(2)=2^2-4$, which skips $f$ and uses $2$ in $g$ directly. Choice H ($16$) squares $f(2)-1=4$ instead of squaring $5$, which does not follow the definition of $g$. The inside function is always evaluated first, and its output becomes the input of the outside function.