It is part of the cell membrane. Last choice.
Answer:a.
Explanation:I took the quiz
The thymus becomes smaller with age as well as decreased immune system function.
The process of shrinking of the thymus is known as involution. This process occurs with any tissue that is not in frequent use. Before an individual reaches adulthood, the immune system has produced most of its T-cells. Therefore, new T-cells do not need to be produced, so the tissue of the thymus gland is replaced by adipose tissue.
. great increase in air, land and water pollution; no one to ensure proper disposal of toxic
