Geometry

Question Analysis：
This question tests understanding of which single angle condition is insufficient to prove a parallelogram.

Key Concept Explanation：
Complete parallelogram proof requires：
• Both pairs of adjacent angles supplementary, OR
• Both pairs of opposite angles equal
Single conditions may be insufficient

Step-by-Step Solution：
Given adjacent angles 65°+115°=180° (one pair satisfied)
Analyze options：
A) ∠G = 65° makes opposite angles equal (65° = 65°) → Valid
B) ∠H = 115° makes opposite angles equal (115° = 115°) → Valid
C) ∠F + ∠G = 180° confirms other adjacent pair → Valid
D) ∠G = 115° shows one pair of adjacent angles is equal → Insufficient

Common Mistakes：
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