B. This document changed the course of U.S. and world history in several ways.
Explanation:
Introductory paragraph must end on note which opens the way for further discussion.
The sentence in Option B shows that the paper will be about how this document changed the course of US history. By using the phrase “several ways”, the student will succeed in engaging the audience to read more about these<em> “several ways”.</em> Moreover this end of the first paragraph is also connected with the title of the paper i.e “Effect of the United States Declaration of Independence”
Sentences in option A, C, and D can be included in the middle of the first paragraph just to give some basic information of the Declaration. But none of them should be at the end of the introductory paragraph as they give no hint about what is to come next in the paper.
