What is the most important role an emt plays in the emergency cardiac care system?

The most important role  an emt plays in the emergency cardiac care system should be  early defibrillation. 
emt should be able to recognize the need for defibrillation  and the ecg reading that need to be defibrillated. emt also have knowledge in advanced life support protocol/algorithm.

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.