Answer:
A. a quotation from the director of an overcrowded animal shelter.
Explanation:
First thing to do, when dealing with this type of questions is to identify and understand the main claim. In this case, it says that adopting dogs from the shelters helps solve the overpopulation problem. So, shelters are overcrowded with dogs and unable to provide adequate care and food for the excess dogs.
Since this claim is dealing with dogs and overcrowded shelters, answers b), c) and d) are completely irrelevant to this topic.
However, a quotation from the director of one such overcrowded shelter could provide quite useful and supporting evidence for this claim.
This quotation could be about the capacity of shelters and the current number of the dogs it holds or about how and why this overpopulation is a problem or about to which consequences can this lead etc.
