Geometry

Question Analysis:
This question evaluates understanding of the relationship between squares and rectangles.
The main focus is identifying the additional property that defines squares.

Key Concept Explanation:
All squares are rectangles (they have 4 right angles and opposite sides equal).
The added requirement for squares is all sides equal, which rectangles do not need.

Step-by-Step Solution:
Option A: True for both shapes but not unique to squares.
Option B: True for both (diagonals are equal in both).
Option C: Correct. Congruent sides are the extra condi...