Sentence C uses a semicolon correctly to connect two independent clauses and includes a transitional phrase. This is proper punctuation for written expression.
Sentence B is correctly structured with a dependent clause ("Although the exam was difficult") followed by an independent clause ("many students managed to pass it"). This shows correct use of complex sentence structure.
Sentence C has correct subject-verb agreement with a collective noun ("The committee was"), which is treated as singular.
Sentence D correctly modifies "dress" with the adjectives "blue and stylish," clearly describing the noun without confusion.
Sentence B clearly and effectively conveys the purpose of the new policy with proper structure and clarity, making it the best choice for written expression.