Why can't I use 'whole stranger' instead of 'perfect stranger'?

Hi. I was solving problems and don't know why my answer is wrong.

The question is

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A : Who is that man standing by the door?
B : I have no idea. He's a _________ stranger to me!
(a) whole
(b) distant
(c) perfect
(d) foreign

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The answer is '(d) perfect'.

But I thought '(a) whole' could be correct.(though now apparently it's not)

Somebody told me it's wrong because of the context.
He thought here we need a word for '100%', and 'whole' means 'almost' or '80~90%'.
Yes, I think it could be, but there were so many other opinions...

Another guy thinks 'whole' means physically all of someting and 'perfect' gives subjective emphasis to the following word,
and the examples are 'whole world' and 'perfect world' .
But I think I've heard 'whole strange things' or something like that... and 'a whole new world'. Am I wrong? ^^;;

Why can't I use 'whole stranger' instead of 'perfect stranger'?
Help me please. I have no clear idea about this(T_T)
Thank you very much in advance!