Choose the word which gives an appropriate meaning of referendum (last line, para 5).
survey
A referendum is a direct vote by the electorate on a particular proposal or issue. It is commonly referred to as a plebiscite, a term used to describe a direct vote by the people on important issues, often constitutional or political. Hence, the correct answer is (C).
The word to be replaced is "referendum," so each option can be checked for whether it carries the same core meaning of a direct public vote on a specific issue.
Only "plebiscite" preserves the exact meaning of a direct, decisive public vote conveyed by "referendum" in the passage.
Hence, the correct answer is Option C.