More specifically, transmission occurs when the agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission, and enters through an appropriate portal of entry to infect a susceptible host. This sequence is sometimes called the chain of infection.
Explanation:
Lymphocytes are the type of the white blood cell which function as a part of immune system.
Types of Lymphocytes:
T cells
T cells are developed in thymus gland. The specialized molecule of T-cell receptor is located on surface of cell. The molecule is important in the immunity as it recognizes the antigens and thus it to bind to them.
B cells
B cells are important part of immune system. They mature in bone marrow of the humans, and in bursa organ of the birds. The cells have a protein on the surface which is known as B-cell receptor. The protein recognizes and attaches to the specific antigens.
Natural killer cells
Natural killer cells are the lymphocytes which are known to be cytotoxic. They have ability to kill the other cells in the body. The cells are important part of immune system because these cells are able to recognize infected cells.
Answer:
b
Explanation:
because that is how we were taught the time i was doing grade 9 & we were given diagram as to show us
