Solve the Problem $\mathrm { A } = \left[ \begin{array} { r r r } - 1 & 1 & 4 \\ 1 & 4 & 3 \end{array} \right]$

Multiple Choice

Solve the problem.
- The matrix $\mathrm { A } = \left[ \begin{array} { r r r } - 1 & 1 & 4 \\ 1 & 4 & 3 \end{array} \right]$ represents the coordinates of the triangle. Find the product $\left[ \begin{array} { r r } 1 & 0 \\ 0 & - 1 \end{array} \right] \cdot \mathrm { A }$ and explain the effect on the graph of the triangle.

A) $\left[ \begin{array} { r r r } - 1 & 1 & 4 \\ - 1 & - 4 & - 3 \end{array} \right]$ ; This matrix represents the reflection of the triangle across the $x$ -axis.
B) $\left[ \begin{array} { r r r } - 1 & 1 & 4 \\ - 1 & - 4 & - 3 \end{array} \right]$ ; This matrix represents the reflection of the triangle across the y-axis.
C) $\left[ \begin{array} { r r r } 1 & - 1 & - 4 \\ 1 & 4 & 3 \end{array} \right]$ ; This matrix represents the reflection of the triangle across the $\mathrm { x }$ -axis.
D) $\left[ \begin{array} { r r r } 1 & - 1 & - 4 \\ 1 & 4 & 3 \end{array} \right]$ ; This matrix represents the reflection of the triangle across the y-axis.