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
Muscle that causes flexion at elbow joint when forearm is semi - pronated 
Select and explain. 
A. Biceps brachii, B. Brachialis, C. Coracobrachialis, D. Brachioradialis
D: Brachioradialis
Answer: D: Brachioradialis 
Explanation: Brachioradialis causes flexion at elbow joint when forearm is semi - pronated.