The answer is the second choice. Parallelograms that are not rectangles do not have congruent diagonals; however, all rectangles do have congruent diagonals. A rhombus has perpendicular diagonals but is not a rectangle, so the first choice is wrong A rhombus has all congruent sides but is not a rectangle, so the third choice is wrong. The last choice only applies to certain quadrilaterals, none of which are rectangles. Question 2: The first choice is the answer. A rectangle has congruent diagonals, but is not a square. We can eliminate the second choice.
A rhombus has all congruent sides, but it is not a square.
The last choice only applies to certain quadrilaterals, none of which are squares.
