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: Anatomy
[{'content': 'Which tendon is frequently absent in upper limb? \nSelect and explain. \nA. Flexor carpi ulnaris, B. Flexor digitorum profundus, C. Extensor carpi radialis brevis, D. Palmaris longus', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The palmaris longus may not always be present. It has a short belly and long tendon. It originates from medial epicondyle of humerus. Distally, it passes over the flexor retinaculum with which its fibers mingle and is attached to the palmar aponeurosis.', 'role': 'assistant'}]