Geometry

Question Analysis:
This question asks for the simplest valid method to prove a parallelogram based on diagonal properties.
The main focus is on selecting the right proof strategy.

Key Concept Explanation:
One of the five classic methods to prove a parallelogram is by showing the diagonals bisect each other.

Step-by-Step Solution:
The diagonals bisect each other: this directly proves a parallelogram.
No need to check sides or angles if diagonal bisection is confirmed.

Option Analysis:
A: Too much work; unnecessary if diagonal info is given.
B: Valid but requires checking parallelism – more complex.
C: Correct – matches the co...