Explain Why the Tip of the Thumb Flexes When Trying

Explain why the tip of the thumb flexes when trying to grasp a piece of paper between the thumb and index finger in a client who has ulnar nerve paralysis.

A) Because the flexor pollicis longus substitutes for the absent adductor pollicis muscle
B) Because the extensor pollicis longus is absent in ulnar nerve injuries
C) Because the index flexor tendons are absent in ulnar nerve injuries
D) Because the thumb opponens pollicis is absent in ulnar nerve injuries