Hello!
The answer is:
B.

Why?
To solve the problem, we need to add/subtract like terms. The like terms are the terms that share the same variable and the same exponent.
For example:

We were able to add the terms that were squared since both shares the same variable and the same exponent.
So, we are given the functions:

Now, we are asked to calculate (f+g)(x) which is also equal to f(x) + g(x).
Then, calculating we have:

Hence, the answer is:
B.

Have a nice day!