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: ENT
Which of the following muscles is responsible for abduction of vocal cord 
Select and explain. 
A. Posterior cricoarytenoid, B. Lateral  cricoarytenoid, C. Cricoarytenoid, D. Transverse arytenoid
A: Posterior cricoarytenoid
Answer: A: Posterior cricoarytenoid 
Explanation: None