Question

Why should a writer place source information in parentheses at the end of a sentence?

to question whether the source is presenting trustworthy information
to give credit to the authors of that source and avoid plagiarism
to indicate that the source is stating the main idea of the paper
to show that the source has published multiple articles on the topic

Answer 1

to give credit to the authors of that source and avoid plagiarism

Parenthetical citations (in-text citations) acknowledge the original source, let readers find the full reference, and prevent plagiarism by showing which ideas or facts came from someone else.