Answer:
a. naturalistic
Step-by-step explanation:
Naturalistic observation: In psychology, the term naturalistic observation is defined as a research method in which the experimenter or the researcher tends to observe the participants involved in his or her research in their natural surroundings or environment.
The researcher or the experimenter then write down everything they have analyzed related to their behaviors and actions.
In the question above, the type of observation involved in the given statement is naturalistic observation.