Final answer:
Killing Anopheles mosquitoes affects Plasmodium protists by preventing the spread of the parasite and interrupting its life cycle, as the mosquito is essential for the parasite's development and transmission to humans.
Step-by-step explanation:
The effect of killing Anopheles mosquitoes on Plasmodium protists is that it prevents the spread of Plasmodium by interrupting their life cycle. Since members of the Plasmodium genus, including Plasmodium falciparum, the primary cause of malaria, require both a mosquito and a vertebrate host to complete their life cycle, targeting the mosquito vector impedes the parasite's ability to propagate. When Anopheles mosquitoes, which transmit malaria to humans, are eliminated, the Plasmodium parasites lose their means of being carried from one human host to another, thus breaking the cycle of infection and disease transmission.
The correct answer to the question is: (a) It prevents the spread of Plasmodium by interrupting their life cycle. This is because Anopheles gambiae mosquitoes play an essential role as vectors, allowing the Plasmodium to complete its life stages that occur within the mosquito, including the development of the sporozoites that are transmitted to humans during a mosquito bite. Without the mosquito vector, Plasmodium cannot continue its life cycle and will not reach the human host, thereby reducing the incidence of malaria.