Correct Answer: C

Rationale: The word 'they' is the best substitute for the underlined words in the sentence because it refers to the plural noun 'nursing students' and is used to indicate the subject of the sentence. Using 'they' maintains subject-verb agreement and clarity in the sentence. Choice A 'them' is incorrect as it is used for objects, not subjects. Choice B 'him' is singular and does not agree with the plural noun 'nursing students.' Choice D 'those' is also incorrect as it refers to objects, not the subject of the sentence.

Correct Answer: A

Rationale: The correct answer is A: 'Period'. The sentence 'Take this fast-acting cough medicine after your next meal.' is a complete sentence and requires a period at the end to indicate a full stop. A comma (Choice B) is not suitable here as it would create a comma splice. A colon (Choice C) is not needed as there is no introductory clause or list following it. A hyphen (Choice D) is used to join compound words or for other specific purposes, not to end a sentence.

Correct Answer: C

Rationale: The word 'draw' is used incorrectly in the sentence. The correct word that needs to be used is 'criteria' instead of 'criterion' to maintain subject-verb agreement. The correct sentence should be: 'Which criteria were used to draw a conclusion about their findings?' 'Draw' should be 'were drawn' to match the plural subject 'criteria.' The other choices are correct in the sentence and do not contain any errors.

Correct Answer: D

Rationale: The word 'prefer' should be changed to 'prefers' to match the singular subject 'Louis.' The correct sentence should be: 'Fredericka always orders pancakes, but Louis prefers waffles.' Choice A 'always,' Choice B 'orders,' and Choice C 'but' are used correctly in the sentence and do not need any corrections.

Correct Answer: D

Rationale: The correct pronoun to use in this sentence is 'themselves' because it refers to the plural noun 'People.' 'Oneself' is singular and does not match the plural subject. 'Themself' is not a standard pronoun in English and is considered non-standard usage. 'Theirselves' is not a proper word in standard English grammar and is grammatically incorrect. Therefore, 'themselves' is the only grammatically correct option in this context.