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
Muscles which open the glottis are: 
Select and explain. 
A. Cricothyroid, B. Thyroarytenoid, C. Posterior cricoarytenoid, D. Lateral cricoarytenoid
C: Posterior cricoarytenoid
Answer: C: Posterior cricoarytenoid 
Explanation: None