Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
Here "its victims" is apropriate as the sentence is talking about
a specific disease. So this gets rid of D and E.
A) Not clear who is inoculated the disease or the victims.
C) Has the same problem.
B) This clearly says who is inoculated. The pronoun "they" clearly refers to its antecedent "victims"
The key to solving such questions is to act a little dumb.
If some one had sent you this sentence in an email you would
probably interpret it correctly because it is common sense. We
all know about this disease. Try explaining it to a person who
has never herd of this disease. It might really confuse that person.