Concept:Secret voting protects the voter's privacy so that no one can force or pressure the voter.Explanation:Secret voting allows a voter to cast their ballot without others knowing their choice.This privacy removes the fear of being punished or threatened.As a result, the voter is free to decide without any external pressure or coercion.It does not prevent the voter from thinking about issues, national interest, or public good.Therefore, the main purpose is to ensure freedom from coercion.Answer:A. coercion