Concept:Public opinion is measured through channels that reach and reflect the views of the people.
Explanation:Mass media, which includes newspapers, radio, television, and online platforms, is a major tool used to gauge public opinion.
It helps in shaping and also in collecting the opinions of the people on various issues.
Mass media is intended to be informative, and it gives citizens a means to express their views.
The constitution, educational institutions, and electoral college do not primarily function as tools for gauging public opinion.
Therefore, mass media is the key instrument for assessing public opinion.
Answer:C. mass media