To correctly demonstrate polynomial addition, we need to add the like terms of the given polynomials. Let's look at the addition in choice C:
\[ (2x^2 + 6x + 1) + (3x^2 + 3x + 9) \]
Now, we'll combine the like terms:
- Combine the \(x^2\) terms: \(2x^2 + 3x^2 = 5x^2\)
- Combine the \(x\) terms: \(6x + 3x = 9x\)
- Combine the constant terms: \(1 + 9 = 10\)
Putting it all together, we get:
\[ 5x^2 + 9x + 10 \]
Now we can compare this result with each option:
- A. \(5x^2 + 9x + 10\) (Correct, but this is a subtraction statement, not an addition).
- B. \(-5x^2 + 3x + 8\) (Incorrect).
- C. \(x^2 + 3x + 8\) (Incorrect).
- D. \(-x^2 + 3x - 8\) (Incorrect).
The correct demonstration of polynomial addition is NOT listed among the choices provided. However, the accurately computed addition is \(5x^2 + 9x + 10\) as shown from the correct calculation steps.
Thus, the answer based solely on polynomial addition should be \(5x^2 + 9x + 10\) but note that none of the choices were correct in demonstrating that operation directly.