8. When a patient receives a vaccine against pneumonia, the patient's immune system produces memory cells. How do memory cells prevent
illness? *
O A) They weaken the pneumonia pathogens
O B) They kill the pneumonia pathogens from the vaccine
C) They produce antibodies quickly the next time pneumonia pathogens invade
OD) They differentiate into B cells that attack the pathogens

Hydrilla (hydrilla verticillata) is an invasive aquatic plant and one of the most serious aquatic pests in florida. hydrilla has already been introduced to hundreds of bodies of water throughout florida, hydrilla is difficult to control because it grows rapidly and survives in many different water depths and conditions. hydrilla • describe how hydrilla affects native plant and animal species. include both a biotic and an abiotic limiting factor. • suggest one biotic and one abiotic recommendation that could slow the spread of hydrilla