D - brisk.
It is basically a synonym for fast and is an adjective which is what is missing .
Answer:
Lymphocytes are white cells that are crucial to our immune systems. There are three main types known as T cells, B cells, and natural killer cells. Lymphocytes are part of our immune defense and act to recognize antigens, produce antibodies, and destroy cells that could cause damage.
The answer is A because all the other answers are unreasonable
All the answers provided are correct.
Disabilities make life in school, and among peers more difficult.
