Which of the following glands plays a key role in the metamorphosis of a frog's tadpole?

Select the incorrect option.

An organ $X$ has a large blood supply. It produces a hormone,the lack of which causes a disease known as cretinism. The organ is

Name the endocrine gland that produces calcitonin and mention the role played by this hormone.

$A$ pregnant lady delivers a baby who suffers from stunted growth,mental retardation,low intelligence quotient and abnormal skin. This is the result of $:-$

Metamorphosis in frog can be promoted by