Which of the following pathogens undergoes antigenic variation to avoid immune defenses?
candida
cryptococcus
plasmodium
giardia

The correct option is : c. Plasmodium

Explanation:

Antigenic variation is a mechanism in which pathogens alter the carbohydrates or proteins present on their surface, to gain immunity from the immune system of the host. This also allows the pathogen to re-infect the previously infected hosts.

Example: The protozoan parasite, Plasmodium falciparum undergoes antigenic variation.

helicase, i think thats it