plane mirror

[evusq]

Hello, I came around more than two questions dealing with the plane mirror, and I don't think I really understand how it works.
Below is the problem I was working on from TBR.

Q: Using a plane mirror that is 1 meter tall would prevent which standing person from seeing approximately their entire body length?

A. Person standing 1m from mirror whose height is 2 meters.
B. A person standing 2m from the mirror whose height is 1 meter.
C. A person standing 4m from the mirror whose height is 0.5 meter.
D. A person standing 0.5m from the mirror whose height is 4 meters.

Answer is D. Actually I got it right this time by guessing, but then the explanation threw me off... can anybody explain this to me please?
I know that for plane mirror, d=d', and h=h'? So at first I thought any height greater than the length of mirror wouldn't be seen in entirety but this is not true.... thanks for help.

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[Seraph 84]

A plane mirror needs to be at least half as long as the person is tall to see the entire reflection. The reason why the distance from the mirror doesn't matter is because the plane mirror can be adjusted vertically. You can use a ruler to convince yourself why this is true.

The person in choice D is 4 times longer than the mirror, so no matter where that person stands, he will never see his entire image. The height of the other people is no more than twice the length of the mirror, so they will always be able to see their entire reflection.