How does natural selection affect undesirable traits?

Natural selection affects undesirable traits, because as time pass on, the undesirable traits will be lost due to the competition with the desirable traits. For an example, the Rabbits that runs slower than normal rabbits, will eventually die due to the natural selection because the normal ones will run faster than the undesirable one. 

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.

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