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: Pediatrics
Commonest cause of hypothyroidism is 
Select and explain. 
A. Defective synthesis of thyroxine, B. Defect of iodide transport, C. Defect of the thyroglobulin synthesis, D. Thyroid dysgenesis
D: Thyroid dysgenesis
Answer: D: Thyroid dysgenesis 
Explanation: (Thyroid dysgenesis) (1872-73-Nelson 17th) (481-Ghai 7th)HYPOTHYROIDISM results from deficient production of thyroid hormone or a defect in thyroid hormone or a defect in thyroid hormonal receptor activity* Someform of thyroid dysgenesis (aplasia, hypoplasia or an ectopic gland) is the most common cause of congenital hypothyroidism, accounting for 85% of cases, 10% are caused by an in bom error of thyroxine synthjesis and 5% are the result of transplacental maternal thyrotropin receptor blocking antibody.* Pendred syndrome - congenital hypothyroidism with sensorineural deafness and goiter, also have a positive perchlorate discharge.* ** Sodium L-thyroxine given orally is the treatment of choices (side effects are - craniosynostosis and temperature problems pseudotumour cerebri)* Acquired hypothyroidism - is most commonly caused by auto immune destruction of thyroid as a part of Chronic lymphocytic thyroidits (Hashimoto's thyroiditis