This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Larynx, Subject name: ENT
Abductor of vocal cord is? 
Select and explain. 
A. Posterior cricoarytenoid, B. Cricothyroid, C. Interarytenoid, D. Lateral cricoaretynoid
A: Posterior cricoarytenoid
Answer: A: Posterior cricoarytenoid 
Explanation: ANSWER: (A) Posterior cricoarytenoidREF: Dhingra 4th ed p. 259Repeat from December 2009, December 2010INTRINSIC MUSCLES ACTING ON VOCAL CORDS:AbductorsPosterior cricoarytenoidAdductorsLateral cricoarytenoid, Lnterarytenoid (transverse arytenoid) Thyroarytenoid (external part)TensorsCricothyroid Vocalis (internal part of thyroarytenoid)INTRINSIC MUSCLES ACTING ON LARYNGEAL INLET:Openers of laryngeal inletThyroepiglottic (part of thyroarytenoid)Closers of larylngeal inletlnterarytenoid (oblique part), Aryepiglottic (posterior oblique part of interarytenoids)