This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: DNB 2018, Subject name: Anatomy
Froment's sign is due to which nerve injury 
Select and explain. 
A. Intercostobrachial, B. Radial, C. Ulnar, D. Median
C: Ulnar
Answer: C: Ulnar 
Explanation: froment's sign / book test : tests adductor pollicis muscle it is innervated by ulnar nerve. in ulnar nerve injury, when pt is asked to grasp a book firmly b/w thumb & other fingers of both hands, the terminal phalanx of thumb on paralysed side becomes flexed at interphalangeal joint (by flexor pollicis longus supplied by median nerve). The signs indicative of ulnar nerve palsy are as follows: Froment's sign: Jeanne's sign: