Geometry

Question Analysis:
This question explores conditions under which a parallelogram becomes a rhombus.
The main focus is side lengths and diagonal intersection.

Key Concept Explanation:
A rhombus is a parallelogram with four congruent sides.
Diagonals in a rhombus are perpendicular.
One pair of adjacent congruent sides in a parallelogram forces all sides to be congruent.

Step-by-Step Solution:
A: All sides equal → rhombus by definition → ✅
B: Diagonals perpendicular → rhombus trait → ✅
C: Already true in parallelogram → doesn’t change the shape → ❌...