The argument in the passage assumes which of the following? A. The difference in the manner in which the infection enters the body is not what causes the difference in the hamster's immune-system response. B. The human immune-system response to injection with Borrelia burgdorferi would be identical to the hamster's immune-system response to injection with that bacterium. C. In the wild, hamsters are at least occasionally infected with Lyme disease by tick bites. D. There are no laboratory-cultured bacteria that would cause the hamster's immune system to react as it does when infected with Borrelia burgdorferi by a tick bite. E. In rodents other than hamsters. the immune-system responses to Borrelia burgdorferi infections both by injection and by tick bite are identical to those in hamsters.