I think A is the youngest layer, because of the new sediments that fell upon the animal.
None of the above... Ingumentary system is the one that regulates body temperature. The ingumentary system is skin, hair , sweat glands and nails
Thyroxine is an important hormone released into the bloodstream by the thyroid gland in the body. When tyroxine is released into the blood stream, it moves through certain organs such as the kidney and liver, where most of it is changed to an active form known as triiodothyronine. Thyroxine perform important roles in brain development, heart and digestive functions, bone maintenance, controlling muscle and metabolic rate of the body.
