Concept:Public opinion is measured through systematic and reliable data collection methods.
Explanation:The mass media needs objective information about the views of the people.
Polls and surveys are structured tools used to gather opinions from a representative sample of the public.
These methods provide measurable and verifiable data on public attitudes.
Influential citizens may express personal views but they do not represent the general public.
Interviews are useful but less systematic and often not broad enough.
Rumors and gossip are subjective, unverified, and unreliable sources.
Propaganda is designed to shape opinion, not to measure it.
Hence, polls and surveys are the most credible means for the media to assess public opinion.
Answer:C. polls and survey