Answer:
The 4th option would be correct.
Explanation:
No complex calculations are needed. Just pay attention to what the problem is asking for. Notice that f(x) is positive while g(x) is negative. So instead of adding, you're subtracting.
Now look at the last coefficients in each function. Notice that they're the same term, since both of their variables are x^2. Since we're subtracting, that 5x^2 in function g is actually going to be negative. This is why the answer would be the last option, since it's the only one that shows that -4x^2 and -5x^2 is being combined.
Also, at the start, I said no complex calculations are needed. This is because the problem didn't say 'Show your work' or something along those lines. Only do it if it asks, or if your teacher does.