Which of the following is an example of a questionnaire?

The census serves as a clear example of a questionnaire because it consists of a structured set of questions designed to gather specific information from a large population. It typically includes various demographic inquiries aimed at collecting data that can be analyzed statistically. The census is distributed to households and completed by individuals, making it a systematic way of collecting quantitative data across diverse communities.

In contrast, face-to-face interviews involve direct interaction with participants and often employ open-ended questions, allowing for more in-depth responses, which is distinct from the structured format of a questionnaire. Focus groups also differ as they are discussion-based, gathering qualitative insights rather than solely relying on pre-defined questions. Data observations pertain to the gathering of information through direct observation of behaviors or settings, which does not involve the use of a questionnaire format. Thus, the census distinctly exemplifies a questionnaire in its standardized approach to data collection.