This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bony dysplasia and soft tissue affection, Subject name: Orthopaedics
Most common cause of trigger finger - 
Select and explain. 
A. Trauma, B. Alcohol, C. Smoking, D. Drug abuse
A: Trauma
Answer: A: Trauma 
Explanation: Trigger finger resulting from constriction of fibrous digital sheath, so that free gliding of the contained flexor tendon does not occur.The underlying cause is unknown but the condition is ceainly more common in patients with diabetes. People with rheumatoid disease may develop synol thickening or intratendinous nodules which can also cause triggering. Occupational factors, though sometimes blamed, are unlikely to be causative. Reference- Apley&;s system of ohopaedics 9th edn- pg no 423.