Why are there four images in two parallel mirrors instead of three?

[alingy1]

Hi Forum,
Simple question here, but one that has been bugging me. Please look at picture.

So, rays from the baseball can go from the lower mirror to the eye. (1 image)
Rays from the baseball go from the upper mirror to the eye. (1 image)
Rays from the baseball go from the lower mirror to the upper mirror to the eye. (1 virtual image behind the upper mirror)
Rays from the baseball go from the upper mirror to the lower mirror to the eye. (1 virtual image behind the lower mirror)

Total of four images.

What's up with the 3 images suggested by the answer booklet?

 

[Doc Al]

Each plane mirror forms an image. Where are those images?

Those images act as virtual objects, forming their own images. Where are those images? (That will give you the answer.)