The correct answers to this question are: -to avoid plagiarism -to direct readers to original sources of information
Without a works cited page, it is considered plagiarism. You must always credit the source of your information and you cannot "steal" the ideas. In addition, a works cited page allows readers to find your research sources. If the paper is to be graded, your teacher also needs a way to find the sources in order to know whether the sources are reliable or not. If you use unreliable sources, it is likely that your paper has some false information.
I hope this helps you! Feel free to comment or PM me if you have any additional questions!