In each of the following questions, two columns are

Solution

The correct pairs are AE, BF, and CD. AE: A tells us that immunisation on a large scale is important for public health while also suggesting that something is controversial. E tells us what is controversial: forcing people to get vaccinated, and also gives the reason for this: diverse ethical and cultural norms. The definite article THE correctly modifies the noun DIVERSITY given in E. "Widespread immunisation is a vital tool for public health but it is much more contentious, given the diversity of humanity's ethical and cultural norms, to impose vaccinations on a population." BF: B talks about a fact related to the immune system: that it uses something that is complex in nature. F tells us what it is: a range of protective mechanisms to control and, most often, eliminate toxins. The adjective COMPLEX is B correctly modifies the noun ARRAY in F. "It is not surprising that the immune system uses a complex array of protective mechanisms to control and usually eliminate toxins." CD: C tells us that societal hesitation is a battle between anti-vaccine groups and the ignorant population against scientific reason and public health, as stated in D. The conjunction AND in C correctly connects two identical parts of speech, which are nouns given in C (anti-vaccine groups) and D (ignorant populations) , respectively. "Societal hesitation about vaccination is a simple battle between anti-vaccine groups and ignorant populations on the one side, and scientific reason and public health on the other." Thus, C is the right answer.