The correct answer is C. Appeal to emotion
Step-by-step explanation:
In rhetoric including text and speeches there are different strategies the author can use to convince or persuade the reader about a certain idea this includes appeal to authority in which the author uses the words and ideas of an external author to support his/her ideas; appeal to logic in which the author uses arguments based on reasoning; appeal to morality in which the author uses the moral principles of the audience to persuade them and appeal to emotion in which the author uses the emotions of the audience.
In the case of the excerpt from "Silent Spring" by Rachel Carson the author describes the way n which a town or place in the country became silent as she states before there were many birds voices but then everything was on silent, besides this, she describes in farms animals were dying and fruit was not growing, roadsides had only browned vegetation, which represents a tragedy. This shows the author uses the contrast between the way different elements were before and the way things changed, which causes feelings such as sadness and nostalgy in the audience which persuade them to believe Carson. Therefore, the strategy used by Carson is an appeal to emotion.