Determinant Row Swap
1. **Problem Statement:** We are given a 3x3 matrix \(M_1 = \begin{bmatrix} a & b & c \\ d & e & f \\ g & h & i \end{bmatrix}\) with determinant \(\det(M_1) = 8\). We want to find the determinant of the matrix \(M_2 = \begin{bmatrix} a & b & c \\ g & h & i \\ d & e & f \end{bmatrix}\).
2. **Recall the determinant property:** Swapping two rows of a matrix multiplies the determinant by \(-1\). This is a key property of determinants.
3. **Analyze the transformation from \(M_1\) to \(M_2\):**
- In \(M_1\), the second row is \((d, e, f)\) and the third row is \((g, h, i)\).
- In \(M_2\), these two rows are swapped: the second row is \((g, h, i)\) and the third row is \((d, e, f)\).
4. **Effect on determinant:** Since \(M_2\) is obtained by swapping the second and third rows of \(M_1\), the determinant changes sign:
$$\det(M_2) = -\det(M_1)$$
5. **Calculate the determinant of \(M_2\):**
$$\det(M_2) = -8$$
6. **Answer:** The determinant of the second matrix is \(-8\), which corresponds to option B.
**Final answer:** \(-8\)