Which of the following statements about positive and negative lymphocyte selection is TRUE?
A. In both instances, lymphocytes die after they do their job.
B. In both instances, antigens do not recognize pathogens in the body.
C. Only positive selection is needed for proper functioning of the immune system.
D. It is necessary to have lymphocytes that can fight invaders without harming the body's own tissues.
Answer: D
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