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
Trigger finger occurs in -a) Rheumatoid athritisb) Traumac) Osteosarcomad) Osteoarthritis 
Select and explain. 
A. ac, B. ab, C. ad, D. bc
B: ab
Answer: B: ab 
Explanation: More common in people with certain medical problems, e.g. Diabetes, Rheumatoid arthritis, Gout, renal disease, Collagen vascular diseases, Dupuytren's disease.
Local trauma is a risk factor
Activities with power grip causes shearing edges of the Al pulley (Pulley of flexor tendon at metacarpophalangeal joint)
Recent surgery