Final answer:
In a research paper, common knowledge is information that does not require citation. Examples of common knowledge include widely known facts like the Earth's orbit around the Sun. Option (B).
Step-by-step explanation:
The type of information that is unnecessary to cite in a research paper is common knowledge. Common knowledge refers to facts that are widely known and easily verifiable by the general public, and thus do not require citation. For example, stating that the Earth orbits the Sun is common knowledge. On the other hand, visuals, professional opinions, and anything from the public domain that is not common knowledge should be cited to credit the original source and avoid plagiarism. Even though public domain materials are not copyrighted, their use in research should be acknowledged if they are not considered common knowledge.
Secondary data in research methods are materials such as books and articles written by other authors about their studies (b. Books and articles written by other authors about their studies).