Final answer:
Malaria, caused by the Plasmodium parasite, uses antigenic variation as an adaptive mechanism to evade the host's immune system, making vaccine development challenging and contributing to its virulence.The correct option is C.
Step-by-step explanation:
One adaptive mechanism used by Plasmodium, the parasite that causes malaria, is antigenic variation.
This process allows the parasite to alter the proteins on its surface, evading detection by the host's immune system.
As the immune system tries to catch up, producing antibodies against one variant of the parasite, Plasmodium has already changed its surface antigens, rendering these antibodies less effective.
This mechanism is one reason why developing vaccines against diseases like malaria and HIV is challenging.
The ability to change and hide from the host's immune system is a key factor in the virulence of the parasite, as it can persist within the host for longer periods, increasing the chances of being transmitted to a new host by a mosquito vector.The correct option is C.