that which VS that VS what

No! C is correct.

But I saw A in Chicken soup for the grieving soul. So I think A has to be correct.

My puzzle focuses on B
i.e.: Is which ommited in A?

I guess B is most likely correct, for the reason that that in B equals to the person/the one. The relative pronoun is which which can be omitted. Do I have any point here?

No, B is the only one that is incorrect.

In ordinary usage, that which and what are interchangeable when they are used as relative clauses. You can almost think of what as a contraction of that which. For example, you can say "What is unfair to you is unfair to me" or "That which is unfair to you is unfair to me." However, you cannot say "That is unfair to you is unfair to me" because that, unlike that which or what, does not (in this case) imply an antecedent noun.

See my comments in your other thread for more details.