Thyroxine is

Goitre occurs due to....

On an educational trip to Uttaranchal,Ketki and her friends observe that many local people have swollen necks. Please help Ketki and her friends to find out the solutions to the following questions.
$(a)$ Which probable disease are these people suffering from?
$(b)$ How is it caused?
$(c)$ What effect does this condition have on pregnancy?

The disease caused by the deficiency of iodine is:

Select the answer which correctly matches the endocrine gland with the hormone it secretes and its function/deficiency symptom.

Metamorphosis in amphibians can be accelerated by