This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Upper limb, Subject name: Anatomy
Froment's sign is characteristically seen in 
Select and explain. 
A. Ulnar nerve injury, B. Median nerve injury, C. Radial nerve injury, D. Intercostobrachial nerve injury
A: Ulnar nerve injury
Answer: A: Ulnar nerve injury 
Explanation: REF.BDC VOL.1.FIFTH EDITION Ulnar nerve injury at the wrist can be tested by Froment's sign,which tests the adductor pollicis muscle.When the patient is asked to hold a book firmly between the thumb and the fingers of both the hands,the terminal phalanx of the thumb on the paralysed side becomes flexed at the interphalangeal joint(by the flexor pollicis longus which is supplied by the median nerve)