This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
Thyroxine is synthesized from which amino acid 
Select and explain. 
A. Arginine, B. Lysine, C. Methionine, D. Tyrosine
D: Tyrosine
Answer: D: Tyrosine 
Explanation: The thyroid hormones, triiodothyronine (T3)and thyroxine (T4), are tyrosine-based hormones produced by the thyroid gland that are primarily responsible for regulation of metabolism. Iodine is necessary for the production of T3 and T4. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as goitre.Ref: Ganong&;s review of medical physiology; 24th edition; page no-341