Answer:
B
Step-by-step explanation:
D: You will not get a cubic function. Nothing adds to give a term with x^3 in it.
C: A rational function is of the form (x^2 + 3x + 2) / (x^2). In other words it has a numerator and a denominator that are polynomials. Unless one or both started out like that, the answer is not a rations function.
A: It can't be linear. The x^2 term will carry over after addition.
The answer is B. One of the polynomials started out as a quadratic. It will remain that way.