Gregory knows that Triangle A B C is reflected onto Triangle A prime B prime C prime. Which statement about the figures is true? If Gregory draws the segment with endpoints A and A’, then the midpoint will lie on the line of reflection.
If Gregory draws the segment with endpoints B and C’, then the midpoint will be on the line of reflection.
Points A and B are equidistant from the line of reflection.
Line segment A B will be perpendicular to the line of reflection.

if Gregory draws the segment with endpoints A and A’, then the midpoint will lie on the line of reflection.

Explanation:

Given that a triangle ABC is reflected in triangle A'B'C'

Here reflection is done on a line

If you imagine the line as a mirror then ABC will have image on the mirror line as A'B'C'

Recall that in a mirror the object and image would be equidistant from the mirror and also the line joining the image and object would be perpendicular to the mirror

But note that corresponding images will only be perpendicular bisector to the line

So A and A' only will be corresponding so AA' will have mid point on line

Option 1 is right