What is the effect of $Thyroxine$ on the metabolic rate?

Read the given statements $:$
$(A)$ Hypothyroidism during pregnancy causes defective development and maturation of the growing baby.
$(B)$ Thyroxine does not require a secondary messenger.
$(C)$ Thyroxine plays a major role in the regulation of Basal Metabolic Rate $(BMR)$.
$(D)$ Hypersecretion of thyroxine could cause immunodeficiency.
How many of the above statements are correct?

Toxic agents present in food which interfere with thyroxine synthesis lead to the development of

Deaf-mutism can be caused due to $:-$

Metamorphosis in frogs is accelerated by $.....$.

Mention the difference between hypothyroidism and hyperthyroidism.