What is the are of parallelogram ABCD?
 AB = BC = CD = DA = 1
 AC = BD = sqrt(2)
I think the answer is B, because we know the diagonal of a square is s*sqrt(2), where s = the length of a side of the square, and if we know the two diagonals of this parallelogram are equal then we know it is a square, right? Can we not assume that the side is 1 given that we know the diagonal?
The OA is: C
C is correct.
It can be rhombus from stmnt 2. Only by combining stmnt 1 , we can prove its a sqaure.