Answer
False
Work Step by Step
We analyze these matrices
$\begin{bmatrix}
1 & 0 \\
0 &-1
\end{bmatrix} $$\begin{bmatrix}
-1 & 0 \\
0 &1
\end{bmatrix}=\begin{bmatrix}
0 & -1 \\
1&0
\end{bmatrix}
$
These matrices is not in form of a strech (the y-axis remain fixed. All other points are moved parallel to the x-axis)
Thus, the statement is wrong.
