Answer: First option.
Explanation:
As the triangle is reflected over the line EG, this means that the distance between each common point of the triangles and the line must be the same for both triangles.
This means that the distance between B and E, is the same distance as the distance between B' and E.
Now, as you know, the midpoint of a segment is a point such that the distance between that point and each endpoint is the same.
So, in the linea AA', the points A and A' are the endpoints, and because F lies in the line of reflection, the distance between A and F is the same distance than in between A' and F.
So F is the midpoint in the line AA'
The correct option would be the first one, F is the midpoint of AA' because the line EG bisects AA', and F is colinear to E and G.