In this question, we are asked to determine the minimum vertical size of a plane mirror for us to see our full image when standing 1m in front of it.

Option 1 states that the mirror should be 0.50m in size. This option is incorrect because a mirror half of our height would not be sufficient to see our full image. We would only be able to see half of our body in the mirror.

Option 2 suggests that the mirror should be 2m in size. This option is also incorrect as a mirror of this size would be too large for us to see our full image. We would not be able to see the entire mirror within our field of vision.

Option 3 provides the correct answer. It states that the mirror should be half of our height. This is the minimum vertical size required for us to see our full image in the mirror. When the mirror is half of our height, it reflects our entire body from head to toe.

Option 4 suggests that the mirror should be twice our height. This option is incorrect as a mirror of this size would be too large for us to see our full image. Again, we would not be able to see the entire mirror within our field of vision.

Therefore, the correct answer