Reflection across y=x is a special case transformation
[tex](x,y) \rightarrow (y,x)[/tex]
The original triangle has vertices A(-5,1), B(-4,3), C(-2,1), D(-3,-1) so the transformed triangle has vertices
A'(1,-5), B'(3,-4), C'(1,-2), D'(-1,-3)
Choice A'(1,-5)
