Reference questions ask about the meanings of pronouns and demonstratives such as they, it, he, she, which, who, that, and this. The goal of these questions is simple: you need to decide what the pronoun or phrase refers to. You probably already do this automatically when you read; if you don’t, then you probably have trouble understanding the reading passages. Reference questions are one of relatively few question types that very basically test a skill that is necessary to read well.
It’s much easier to show what reference questions are like than it is to explain them, so let’s go ahead and look at an example:
Although people commonly associate the word clone with modern scientific advancements, its usage in botany (the study of plants) is far removed from those developments; a clone is, in the world of plants, a completely natural thing, even a common one. Generally speaking, a clone is an individual which is genetically identical to its progenitor, the parent from which the clone was produced. In this type of procreation, only one progenitor is necessary. There are, of course, relatively few animals which reproduce in this way. While certain types of fish, reptiles, and insects (among others) do reproduce asexually, most creatures from the animal kingdom are born from two parent individuals with two discrete sets of genes. In comparison, plants frequently reproduce asexually, creating genetically identical offspring, or clones. The term for this type of procreation is vegetative reproduction, which includes a number of different processes by which various plants multiply.
The phrase “this type of procreation” refers to
(A) becoming genetically identical
(B) reproduction by cloning
(C) birth to a pair of parents
(D) producing individual sets of genes
The answer to a reference question is almost always going to be stated before the pronoun in question is used (there are exceptions, but this is a good general rule). But don’t simply look in the previous sentence; it’s possible that the reference is even earlier than that (two or three sentences before the pronoun) or in the same sentence, sometimes appearing after the pronoun in question.
In this case, we know that “this type of procreation” actually refers to “vegetative reproduction” by the sentence it’s in. But notice that “vegetative reproduction” isn’t in the answer choices. Still, it helps to know that “procreation” is a type of reproduction, meaning a way to create more plants. From that information, we can cross off A and D, which don’t describe types of reproduction. Then, if we read the sentence before the one containing “this type of procreation,” we see that at that point in the paragraph, the author is describing plants that reproduce and create clones. That matches (B) nicely.