This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharynx, larynx and trachea and cranial nerves 3,4,6, Subject name: Anatomy
Which muscle is responsible for abduction of vocal cord, in the given diagram 
Select and explain. 
A. A, B. B, C. C, D. D
C: C
Answer: C: C 
Explanation: A - Lateral cricoarytenoid muscle. B - Inter arytenoid muscle C - Posterior cricoarytenoid muscle D - Cricothyroid muscle