Geometry

Question Analysis：
This question compares the properties of a special parallelogram (rectangle) with those of all parallelograms.
The main focus is on identifying unique rectangle properties.

Key Concept Explanation：
A rectangle is a type of parallelogram, but has additional properties:
All angles are 90°
Diagonals are congruent
However, perpendicular diagonals are a property of rhombi, not rectangles.

Step-by-Step Solution：
A: ✅ Diagonals are congruent in rectangles
B: ✅ Rectangles have 4 right angles
C: ❌ True for all parallelograms, not unique
D: ❌ True for all parallelograms
E:...