Final answer:
The answer is 'C) Passive', as passive observation is a method typically used in research studies to observe existing situations without manipulation.
Step-by-step explanation:
The question is asking about the types of observations that are typically made in research studies when existing situations are being examined without manipulation. The answer to "Such methods typically involve ___ observations of existing situations." is C) Passive. In a passive observation, researchers do not intervene with the study subjects or variables; they merely record what occurs naturally. This contrasts with experimental research, where researchers would directly manipulate variables to observe outcomes. Observational studies can be very informative, especially in cases where it's not feasible or ethical to conduct experimental research. They allow researchers to collect data on natural behaviors and phenomena over time.