Final answer:
Disguised vs. undisguised is a classification in naturalistic observation, with disguised observation hiding the researcher's presence to maintain data validity, and undisguised revealing the observer, which might influence subjects' behavior.
Step-by-step explanation:
The classification of disguised vs. undisguised pertains to a method of observation often referenced in social science research. The question is asking about a type of observation where researchers may either conceal or reveal their presence and purpose to the subjects being observed. The correct answer here is c) Naturalistic observation, which can be divided into disguised and undisguised naturalistic observation. In disguised naturalistic observation, the observer remains hidden or conceals their intent from the participants to avoid influencing their behavior, thus collecting data in a realistic setting that enhances the accuracy and ecological validity of the study. On the other hand, in undisguised naturalistic observation, the participants are aware they are being observed, which may affect their behavior and thereby potentially compromise the validity of the data collected.