Which one of the following statements about the trypanosome causing African sleeping sickness does not explain why the disease has been difficult to control?
A. Trypanosomes have many variable antigen genes.
B. Rearrangement of antigen genes takes place during the asexual cycle.
C. Only one gene determining the antigenic nature of the glycoprotein coat is expressed at a time.
D. By infesting the red blood cells, trypanosomes can "hide" from the immune system.
E. Trypanosomes have a protective glycoprotein coat.
Answer: D
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