Answer:
C.
Explanation:
The Obligation to Endure is one of the chapters in the book of Silent Spring.
In her books she warns about the alarming effects of pesticides on environment.
In this exceprt, she develops the tone by providing the information that provides perspective on today's situation. The tone developed by Carson is insistent. The author is insisting to her audience to pay attention towards the issue she's raised.
Therefore, option C is correct.