Answer: a. it must be a rhombus
Explanation:
- A rhombus is a a parallelogram with four equal sides and of opposite angles are equal. The diagonals of rhombus are perpendicular bisector of each other.
A rhombus with interior angle 90° is square.
A square is always a rhombus because it satisfies all the properties of rhombus but a every rhombus cannot a square.
Therefore, If KLMN is a square, then it must be a rhombus.