Without being noticed and without interfering, Professor Holmes and her students observe and record the willingness of boys and girls to volunteer for an elephant or a donkey ride at the local zoo. Professor Holmes and her students are using which research method?

Naturalistic observation

Explanation:

Naturalistic observation: In psychology, the term naturalistic observation refers to one of the research methods that is being used by various social scientists as well as psychologists to study the participants or subjects involves in the research or study by simply observing them in their natural condition or environment.

The experimenter conducting the naturalistic observation generally observes the spontaneous behavior of the subjects or the participants in a natural context and therefore the experimenter record everything they see.

Naturalistic observation is often being used in qualitative research or experiment.

In the question above, Professor Holmes and her students are using naturalistic observation.