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: Orthopaedics
Sudeck's atrophy is associated with -a) Osteoporosisb) Osteophyte formationc) Osteopeniad) Osteochondritis 
Select and explain. 
A. a, B. ac, C. ad, D. b
B: ac
Answer: B: ac 
Explanation: Initial stages of RSD shows spotty osteoporosis (osteopenia).
While in later stages there is characteristic diffuse homogenous osteoporosis (osteopenia).