✅ Option D is correct because "on" is a preposition, and prepositions require the objective case for the pronouns that follow them. "Us" is the objective case of "we", and it correctly functions as the object of the preposition "on". The appositive "the core team members" further clarifies "us" without altering its required case.

❌ Option A is incorrect. "To" is a preposition, and therefore the pronouns following it should be in the objective case ("her" and "me"), not the subjective case ("she" and "I"). The correct form would be: "The award... was presented to her and me."

❌ Option B is incorrect. After a linking verb (like "was" in "it was"), a pronoun acting as a subject complement should be in the subjective case. Therefore, "them" should be "they" (e.g., "it was they who clarified").

❌ Option C is incorrect. The phrase "except for" functions prepositionally; "for" is a preposition requiring its objects to be in the objective case. Thus, "he and she" should be "him and her" (e.g., "Everyone, except for him and her, had submitted...").

✅ Option B is incorrect because 'to' is a preposition, and personal pronouns following a preposition must be in the objective case. Therefore, "she" should be "her" and "I" should be "me". The correct phrase would be "to her and me".

Preposition + Objective Case Pronoun(s)

❌ Option A is correct. "For" is a preposition, and "them" and "us" are correctly used in the objective case following it, even in a comparative structure.

❌ Option C is correct. "His" is a possessive pronoun used correctly as a subjective complement (predicate nominative) here, referring to the fault belonging to him.

❌ Option D is correct. "My sister and I" forms a compound subject, requiring the subjective case pronoun "I". "Ourselves" is a correctly used reflexive pronoun, referring back to the subject "My sister and I".

✅ In option C, "were" is a linking verb, and "we" functions as a predicate nominative, renaming the subject "The only participants remaining after the initial round." Pronouns acting as predicate nominatives must always be in the subjective case, and "we" correctly fulfills this role.

❌ Option A uses "I" after the preposition "to." Pronouns serving as objects of prepositions must be in the objective case ("me"), so the correct form would be "given to him and me."

❌ Option B uses "her" after the linking verb "was." As a predicate nominative (renaming "It"), the pronoun should be in the subjective case ("she"), not the objective case ("her"). The correct form would be "It was she who..."

❌ Option D uses "I" after the preposition "between." Similar to option A, pronouns functioning as objects of prepositions require the objective case ("me"), making the correct phrase "Between you and me."

✅ The phrase "Dr. Ramirez and _____" acts as an appositive, which renames the subject "The main proponents of the reform."

Since "The main proponents" is the subject of the sentence (and therefore in the subjective case), the pronoun within the appositive must also be in the subjective case.

"She" is the subjective personal pronoun, correctly matching the case of the noun it renames.

❌ "Her" is an objective case pronoun; it would be used if the appositive renamed an object or followed a preposition.

❌ "Them" is an objective case pronoun, unsuitable for an appositive renaming a subject.

❌ "Us" is an objective case pronoun, incorrectly used where a subjective pronoun is required for the appositive.

✅ The correct answer is "she" because in comparative clauses introduced by "than" or "as," the pronoun's case depends on whether it functions as the subject or object of an implied verb.

In this sentence, the full implied comparison is "No one in the department works harder than she works (or she does) when a deadline looms."

Since "she" is the subject of the implied verb "works" or "does," the nominative (subjective) case is required.

❌ Option A, "her," is in the objective case, which would be incorrect as it would imply "No one works harder than [works upon] her," changing the meaning entirely.

❌ Option C, "herself," is a reflexive or intensive pronoun and is not appropriate here as it does not refer back to the subject of an action performed by that subject on itself, nor is it used for emphasis in this context.

❌ Option D, "them," is in the objective case and is also plural, neither of which fits the context of comparing individual work ethic where a nominative singular pronoun is expected.