Which sentence correctly uses the subjunctive after a verb of demand, suggestion, or insistence?

Principle: in formal subjunctive constructions after verbs such as insist, suggest, demand, recommend, decree, and require, the base form of the verb is used. So "I insist that you be quiet" is correct. Step by step: (1) After "insist that," English uses the subjunctive base verb, not an infinitive or ordinary finite form. (2) Therefore "be" is correct, even though the subject is "you." (3) Option A is wrong because after "decreed that," the formal pattern is "the Centre take charge," not "will take." (4) Option B is wrong because the chapter prefers "suggested that we go" rather than "should go" in this structure. (5) Option D is wrong because unreal present conditions take "were," not "was": "If I were the prime minister..." So C is the only option that correctly applies the subjunctive rule.