Answer:
C/D, which you wrote the same answer.
4x² + 3x + 4
Explanation:
The two polynomials are added, so we can remove the brackets:
(x² + 2x + 3) + (3x² + x + 1)
= x² + 2x + 3 + 3x² + x + 1
= x² + 3x² + x + 2x + 1 + 3 <=rearrange by like terms (same variable)
= 4x² + 3x + 4 <=after collecting like terms