What happens at the end of the chain in figure 9.3? ; a) 2 electrons combine with a proton and a molecule of nad���.; b) 2 electrons combine with a molecule of oxygen and two hydrogen atoms.; c) 4 electrons combine with a molecule of oxygen and 4 protons.; d) 4 electrons combine with four hydrogen and two oxygen atoms.; e) 1 electron combines with a molecule of oxygen and a hydrogen atom.

4 electrons combine with four hydrogen and two oxygen atoms

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.

It is used to during sexual reproduction between humans