It’s best to keep the purpose of the study’s research from the subjects in order to keep their involvement private

The statement is false.

Explanation:

While conducting research, if the researcher is planning to conduct interviews, surveys, or observation, whether it is participant or non-participant he must inform the purpose of the study to the subjects when seeking for their permission.

Ethically, the researcher has the obligation to disclose as much information of the study to the subjects, so that they can take an informed decision if they want to participate.

where is your diagram?

it should be d or b but i'm sure it's d