Final answer:
The correct answer is option a) Refer to the same concept in research.
Step-by-step explanation:
The terms participants and subjects refer to the individuals included in a research study, but their usage can differ based on the context of the study. In experimental research, where an intervention or treatment is applied and its effects are measured, the individuals involved are often referred to as participants because they are actively taking part in the research process.
In contrast, in observational studies, where researchers do not apply treatments but rather observe and measure variables of interest in their natural setting, the individuals are sometimes called subjects since they are not actively participating in an intervention. Nonetheless, it is essential to note that the usage of these terms in research can be interchangeable, and it's more about the preference of the research community or specific fields.
In light of the provided context, the correct answer is (a) Refer to the same concept in research, because both terms refer to human individuals who are included in research studies, regardless of whether the study is experimental or observational in nature.