Question

................ should be present in the water for metamorphosis of tadpoles
a chlorine
B carbon
C sulphur
D iodine

Answer 1

iodine is the correct answer.

Answer 2

D) Iodine is a necessary element that should be present in water so that the tadpoles can perform metamorphosis.

The metamorphosis happens due to the presence of the thyroxine hormone.

For the production of thyroxine hormone, it is necessary to have iodine because it is in the presence of iodine that the thyroid gland produces metamorphosis.

This is why it is necessary to have some extracts of iodine in water for the tadpoles to metamorphosis.