Given is function f(x) = x² + 3, and function g(x) = x - 7.
It says to perform the addition operation on functions such that (f+g)(x).
We can simply add the functions as follows :-
(f+g)(x) = f(x) + g(x)
(f+g)(x) = (x² + 3) + (x - 7)
(f+g)(x) = x² + 3 + x - 7
Arranging terms in decreasing order of their degree;
(f+g)(x) = x² + x + 3 - 7
Combining like terms;
(f+g)(x) = x² + x - 4
Hence, option C is correct i.e. (x² + x - 4).