Answer:
C. In the first, introductory paragraph of the essay.
Explanation:
A thesis statement is very crucial to an effective research paper as it presents the major argument to the readers. Thus, it is significant to place it at first, at the very beginning of the paper i.e. at the end of the first paragraph as it would hint the audience of the central idea of the author behind the work. The rest part of the paper contains the evidence to substantiate the chief argument in order to persuade the readers to understand and believe the author's logic or perception. Hence, providing the thesis statement at first would set the flow of the papers and add to the inquisitiveness among the readers, that is how would the author illustrate his argument.
