After reading the sentence "<span>The student representatives will have to dissent and express an unpopular opinion about the proposal." the best replacement for dissent is deviate. The correct answer is C. </span>
Explanation: synonyms of differ are dissent, be at variance, be in dispute, be in opposition, take issue, conflict, clash, cross swords, lock horns, be at each other's throats. And in the sentence the student representatives will have to be in opposition and claim an unliked opinion.