both "proof +of noun" and "proof +that-clause" are correct idioms.
but we need a logic relation between two entities to make an idiom logic and correct
proof of his existence
is correct
poof of him
is incorrect
this is most basic thinking of GMAT SC.
in our problem, "proof of card, or of subject" is not logic. that is all. nothing more.
but we need a logic relation between two entities to make an idiom logic and correct
proof of his existence
is correct
poof of him
is incorrect
this is most basic thinking of GMAT SC.
in our problem, "proof of card, or of subject" is not logic. that is all. nothing more.
