The blue triangle has been reflected to the red triangle. Choose the matrix which made this transformation.

Answer:
B) [tex]\left[\begin{array}{cc}1&0\\0&-1\end{array}\right][/tex]
Step-by-step explanation:
When the coordinates are represented by a column vector, the vertical reflection transformation (x, y) ⇒ (x, -y) looks like the matrix of answer choice B.