Select the word or phrase that makes the following sentence grammatically correct. The students promised ___________ themselves with quiet dignity.
Correct Answer: C
Rationale: The correct answer is C. The sentence requires an infinitive form of the verb 'to conduct' after the verb 'promised.' This structure is commonly used in English grammar, where the main verb 'promised' is followed by an infinitive verb form. Therefore, the sentence should read: 'The students promised to conduct themselves with quiet dignity.' Choice A ('conduct') is incorrect as it is not in the infinitive form required after 'promised.' Choice B ('conducting') is incorrect as a gerund does not fit the grammatical structure of the sentence. Choice D ('to be conducted') is incorrect as it changes the meaning of the sentence, suggesting that someone else will conduct the students, rather than the students conducting themselves.