This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Voice and Speech Disorders, Subject name: ENT
Males have deeper voice when compared to females because of: 
Select and explain. 
A. Long vocal cord, B. Increased vibration due to testosterone, C. Infrathyroid position of larynx, D. Thickened arytenoids
A: Long vocal cord
Answer: A: Long vocal cord 
Explanation: Ans: A (Long vocal cord) Ref: Diseases of the Ear, Nose and Throat by PL Dhingra, 5th edn., 2010, pg: 334Explanation:Both males and females have a high pitched voice in childhood.In males however after puberty the vocal cords lengthen and thicken and this leads to a lower pitched and deeper voice.The growth of the larynx is influenced by testosterone.Failure of this change in males leads to persistence of high pitched voice and is called as Puberophonia (Mutational Falsetto Voice).