our thyroid glands plays a main role in a human body. It secretes thyroxine and calcitonin. In which thyroxine help in growth and cellular metabolism and calcitonin helps to regulates calcium concentration in blood . If thyroid gland stops working then there is low level of calcium in our blood, which leads to mental and hormonal disorder. In this way a person's blood calcium level would be affected if his/her thyroid gland stops working.
DNA is a dynamic and adaptable molecule. As such, the nucleotide sequences found within it are subject to change as the result of a phenomenon called mutation. Depending on how a particular mutation modifies an organism's genetic makeup, it can prove harmless, helpful, or even hurtful.
Mutation (A)
I would say a (Sorry if i am wrong)