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 muscle acts as abductor of vocal cords? 
Select and explain. 
A. Lateral cricoarytenoid, B. Posterior cricoarytenoid, C. Anterior, cricoarytenoid, D. Cricothyroid
B: Posterior cricoarytenoid
Answer: B: Posterior cricoarytenoid 
Explanation: Posterior Cricoarytenoid Muscle: The posterior cricoarytenoid muscle arises from the posterior aspect of the cricoid cailage and courses upward and laterally to attach to the muscular process of the arytenoid cailage. Its contraction pulls the muscular process backward and rotates the arytenoid cailage around a veical axis so that the two vocal processes are abducted and the size of the rima glottidis is increased.