Geometry

Question Analysis：
This question tests recognition of complete versus partial angle conditions for parallelogram proof.

Key Concept Explanation：
Complete proof requires either：
Both pairs of opposite angles equal, or
Both pairs of adjacent angles supplementary

Step-by-Step Solution：
Evaluate options：
A) Sum ≠ 180° → invalid
B) Only one adjacent pair supplementary → incomplete
C) Only one opposite pair equal → incomplete
D) Shows：∠W + ∠Z = 180° and ∠X = ∠Z, then ∠W + ∠X = 180°
So both pairs of adjacent angles supplementary → sufficient
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