Apathogen that is capable of antigenic variation can a) cause fever, low blood pressure, and bleeding problems b) lyse host cells c) avoid host immune defenses d) adhere tightly to host tissues

c) avoid host immune defenses

Explanation:

Antigens are the specific molecules associated with pathogens. These antigens are recognized by the cells of the immune system to generate the immune response. In the case of adaptive immunity, the quick and stronger immune response to the same pathogen is generated when the memory cells recognize the antigens during the second encounter.

If a pathogen exhibits antigenic variations, it means that it is able to synthesize different antigens (mostly proteins and carbohydrates). The cells of the immune system would not be able to identify the pathogen. So, a pathogen with antigenic variations can easily escape from the immune responses of the host cell.