"When conducting research with Spanish-speaking participants, it is often necessary to first provide a description of the study purpose in Spanish. What ethical principle of research does this relate to

The correct answer is: The "informed" portion of informed consent.

Explanation:

While conducting research it is important to let the subjects of the research know what type of information they will disclose, what the purpose of the research is, and make clear that their help is voluntary, thus, they can decide whether to continue being part of the study or not.

Among those guidelines, the informed portion of the informed consent establishes that the target subjects must clearly understand the parameters above described. If translations or interpretations are needed, the researchers must provide them.