Ignore the rotation 90 clockwise

A reflection about y=x

Step-by-step explanation:

The 4 transformations are

Let eliminate which ones won't work.

A translation wouldn't flip the triangle in a different direction after translating it so we won't translate it.

A dilation changes the length for the triangle but the triangles are congruent so we won't dilate it.

A rotation about the orgin wouldn't work nor a specific point so a rotation isnt going to work.

A reflection will work so what will we reflect about.

A reflection makes a reflected point equidistant from the line of reflection and their original point is equidistant from line of reflection.

So let find the midpoint of all the points and find a line where all of them are on.

The midpoint respectively are

Let find the line that includes both these points.

So this means our slope is x. The y value corresponds with the x value so the answer is

So the answer is

"A reflection about y=x