Let's examine each of the given expressions and match them with the provided expressions A, B, and C.
1. For the expression [tex]\( (3x^2 - 7x + 14) + (5x^2 + 4x - 6) \)[/tex]:
- Combine like terms:
[tex]\[
(3x^2 + 5x^2) + (-7x + 4x) + (14 - 6) = 8x^2 - 3x + 8
\][/tex]
- This matches expression [tex]\( B \)[/tex].
2. For the expression [tex]\( (2x^2 - 5x - 3) + (-10x^2 + 2x + 7) \)[/tex]:
- Combine like terms:
[tex]\[
(2x^2 - 10x^2) + (-5x + 2x) + (-3 + 7) = -8x^2 - 3x + 4
\][/tex]
- This matches expression [tex]\( A \)[/tex].
3. For the expression [tex]\( (12x^2 - 2x - 13) + (-4x^2 + 5x + 9) \)[/tex]:
- Combine like terms:
[tex]\[
(12x^2 - 4x^2) + (-2x + 5x) + (-13 + 9) = 8x^2 + 3x - 4
\][/tex]
- This matches expression [tex]\( C \)[/tex].
Therefore, the correct answers are:
[tex]\[
\boxed{B}
\][/tex]
[tex]\[
\boxed{A}
\][/tex]
[tex]\[
\boxed{C}
\][/tex]