What is a characteristic of images formed in plane mirrors?

Images formed in plane mirrors have a specific set of characteristics that set them apart from images produced by other types of mirrors. One of the primary features is that they are upright, meaning they maintain the same orientation as the object being reflected. Additionally, these images are the same size as the object, rather than being smaller or larger.

When you look into a plane mirror, the reflection is essentially a mirror image of you that is identical in shape and size, which is why it is commonly said they are 'virtual images'. These images appear to be located behind the mirror at the same distance as the object is in front of it. This consistent nature of the reflection helps to reinforce why plane mirror images are both upright and the same size as the object.

Hence, the chosen answer correctly reflects these characteristics of images formed by plane mirrors.