Geometry

Question Analysis:
This question involves recognizing and applying a condition that proves a quadrilateral is a parallelogram.
The main focus is on the criterion that one pair of opposite sides is both congruent and parallel.

Key Concept Explanation:
One of the properties that guarantees a quadrilateral is a parallelogram is:
If one pair of opposite sides in a quadrilateral is both congruent (equal in length) and parallel, then the quadrilateral is a parallelogram.

Step-by-Step Solution:
The given information states that AB ∥ CD (parallel) and AB = CD (congruent).
This satisfies the condition that one pair of opposite sides is both congruent and parallel.
According to the theorem, this is sufficient to conclude that ABCD is a parallelogram.

Option Analysis:
A. Rectangle – Incorrect. A rectangle is a special type of parallelogram, but to prove it's a rectangle, we need to show all angles are right angles or diagonals are congruent. Not enough information here.
B. Trapezoid – Incorrect. A trapezoid only has one pair of parallel sides, and congruence is not required. This doesn't align with the given condition.
C. Parallelogram – Correct....