Select the word or phrase that makes this sentence grammatically correct.

Economics ------- my least favorite subject at school.

The correct anwer is D. Her. Since "my mother" is possessive, we need a possessive pronoun to indicate ownership. "Her" is the correct possessive pronoun in this context. Therefore, option D is the correct choice.

The correct article to use in this sentence is "an" instead of "a." The word "error" starts with a vowel sound, specifically the sound /i:/, so it requires the indefinite article "an" before it. Therefore, the corrected sentence would be: "The nurse made an error with the medication, so the doctor made notes about it in the patient's record."

The options B. "Made," C. "With," and D. "about it" are used correctly in the sentence. It is only the incorrect use of "a" that makes the sentence grammatically incorrect.

In this sentence, the adverb "badly" is used to modify the verb "performed." It correctly describes the manner in which Mona performed during dance class. Adverbs are used to modify verbs, adjectives, or other adverbs, and in this case, "badly" modifies the verb "performed" to indicate that Mona's performance was not satisfactory.

In this sentence, the pronouns "He" and "I" are used correctly as the subjects of the sentence. When referring to multiple people, the subject pronouns "he" and "I" are used instead of the object pronouns "him" and "me." Therefore, option A is the correct choice.

Option B is incorrect because it uses "Him and I" instead of "He and I." Option C is incorrect because it uses "Me and him" instead of "He and I." Option D is incorrect because it uses "Him and me" instead of "He and I."