While most organs will grow until maturity (when you stop getting taller), the will get bigger throughout childhood, but it will slowly shrink from once an individual reaches puberty and will continue to shrink throughout adulthood. as this gland shrinks, its tissues are replaced by tissues that are stored in fat cells (called adipose tissue). the reason it shrinks is because the thyroid has a reduced role during adulthood.

The correct answer is "thymus".

Explanation:

The thymus is a lymphoid organ which main function is to produce T cells used for protection in the immune system. While most organs grow until maturity, the thymus stops growing at puberty and starts to shrink throughout adulthood. The reason of the shrinking is that the thymus as a reduced role in adulthood because most of the T cells are produced during childhood. As the thymus shrinks, its tissue is replaced by adipose tissue.

the electromagnetic energy from the sun arrives in the form of visible and invisible light.