A person who has a weakened immune system may not be able to fight against infection because.. pathogens may enter the body and cause illness.
phagocytes many enter the body and cause illness.
normal cells crowd out unhealthy cells.
of an increase in the production of antibodies.

Asample of digestive juice was removed from the stomach of a pig. the juice was placed in a test tube along with some grains of wheat. a second test tube was set up containing an equal number of wheat grains, with distilled water rather than digestive juice. the test tubes were kept for 8 hours at 40 degrees c. after 8 hours, the grains inside the digestive juice had broken into tiny particles. the grains of wheat, in the water, were wet but otherwise unchanged. what is the control group?