PREP的pack3题目，求解答

sehun25

想问下，题目中不是说了deer可以在三个时期都感染上lyme，为什么还选B呢

sehun25

lyme disease is caused by a bacterium transmitted to people by deer ticks.Deer ticks are almost never born infected with bacterium,but they can pick it up from feeding on an infected host in any of the tick’s three successive stages of development:larva,nymph,adult.Once infected, a tick remains infected through any subsequent developmental stages,but since a tick feeds on only one host in each stage, it follows that ________

sehun25

B：people cannot be infected by a tick that picked up the Lyme disease bacterium in the adult stage