This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Sudeck's atrophy is associated with: 
Select and explain. 
A. Osteoporosis, B. Osteophyte formation, C. Osteopenia, D. Osteochondritis
C: Osteopenia
Answer: C: Osteopenia 
Explanation: C i.e. Osteopenia