Step 1: Clarify designs.
• Participant observation: researcher {joins} the group/activity.
• Non-participant observation: researcher stays external; records behavior without participating—often reduces role-conflict but may heighten reactivity if conspicuous.
Step 2: Distinguish from interviews.
Interview is an elicitation method (not pure observation).
Step 3: Conclude.
$$
\boxed{\text{Option C}}
$$