The three main causes of death - cancer, heat disease, and injury, remain constant throughout life. following answers: truth false

These all are true cancer is a main cause, injury is as well. But, there is no such thing as heat disease, there is heat illness or exposure to heat that is a cause of death but not a main one. Now if it is heart disease than yes that is also a main cause of death. Hope this helps :P

answer: - b cells

explanation: -

there are many types of white blood cells present in our body. one such class of white blood cells are the lymphocytes. the b cells belong to the lymphocyte class of wbcs. the b cells perform their action against the pathogen by producing specialised proteins called as antibodies. these antibodies are produced as and when the b cells encounter pathogens in response to the antigens present on the surface of the pathogen. these antibodies bind to the antigens present on the pathogen and then, target them for destruction by other cells of the immune system.

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.