Explanation:
To find the sum of the first 12 terms of the arithmetic sequence, we need to use the formula for the sum of the first \( n \) terms of an arithmetic sequence:

\[
S_n = \frac{n}{2} \times (2a + (n - 1) \times d)
\]

where:
- \( n \) is the number of terms,
- \( a \) is the first term,
- \( d \) is the common difference,
- \( S_n \) is the sum of the first \( n \) terms.

From the previous calculations, we found:
- The first term \( a = -10 \),
- The common difference \( d = 8 \).

Given \( n = 12 \), we need to find \( S_{12} \).

Step-by-Step Calculation:

1. Substitute the values into the sum formula:

\[
S_{12} = \frac{12}{2} \times (2a + (12 - 1) \times d)
\]
\[
S_{12} = 6 \times (2 \times (-10) + 11 \times 8)
\]

2. Calculate inside the parentheses:

\[
2 \times (-10) = -20
\]
\[
11 \times 8 = 88
\]
\[
2a + (n - 1) \times d = -20 + 88 = 68
\]

3. Calculate the sum:

\[
S_{12} = 6 \times 68 = 408
\]

The sum of the first 12 terms of the sequence is 408.

The correct answer is D. 408.