A child has been diagnosed with cretinism. The most likely cause is:

1. Cretinism is a condition of stunted physical and mental development from infancy. 2. It is caused by a **lack of thyroxine** in early life (often due to iodine deficiency). 3. Excess insulin causes hypoglycaemia, not cretinism; excess adrenaline gives anxiety symptoms. 4. Deficiency of growth hormone causes dwarfism — short stature without mental delay. 5. Hence cretinism is caused by thyroxine deficiency from birth. _Source: Selina Concise ICSE Class 8 Biology Ch 5 "Endocrine System and Adolescence", Hormone-related disorders_