Final answer:
The excerpt from Silent Spring that best appeals to readers' pathos is the one that highlights the real-world impact and potential tragedy of environmental disasters. The correct answer is option 4.
Step-by-step explanation:
The excerpt from Silent Spring that best appeals to readers' pathos is: "Yet every one of these disasters has actually happened somewhere, and many real communities have already suffered a substantial number of them. A grim specter has crept upon us almost unnoticed, and this imagined tragedy may easily become a stark reality we all shall know." This excerpt appeals to readers' pathos by highlighting the real-world impact and potential tragedy of environmental disasters, invoking a sense of fear and concern.