Geometry

Question Analysis:
This question tests the fundamental definition of a trapezoid among quadrilaterals.

Key Concept Explanation:
A trapezoid is defined as a quadrilateral with exactly one pair of parallel sides.
Other options describe parallelograms (A), rhombuses (C), or rectangles (D).

Step-by-Step Solution:
Recall the definition: A trapezoid has only one pair of parallel sides.
Evaluate each option:
A: Two pairs → parallelogram (not trapezoid).
B: Exactly one pair → matches definition.
C: Four equal sides → rhombus (could be parallelogram).
D: Four right angles → rectangle (parallelo...