Extract:
Select the word that makes the following sentence grammatically correct.
One of the students ____________ completed the course.
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A
have
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B
has
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C
are
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D
is
The word "has" makes the sentence grammatically correct because the singular subject "one" requires singular verb agreement despite the plural noun "students" in the prepositional phrase.
A) have
"Have" is plural verb form—incorrectly matches the plural "students" in the prepositional phrase rather than the true singular subject "one." Verb agreement follows the subject head noun.
B) has
"Has" is singular verb form correctly matching singular subject "one." Prepositional phrases like "of the students" modify the subject but don't affect verb agreement—the head noun "one" governs verb number.
C) are
"Are" is plural verb form—completely incorrect for singular subject "one." Additionally, "are completed" creates passive voice unnecessarily complex for this context.
D) is
"Is" is singular verb but creates ungrammatical construction "is completed" without auxiliary for passive voice in this context. "One... is completed" illogically suggests the student was completed rather than completing the course.
Conclusion
Verb agreement follows the grammatical subject—not nouns within modifying prepositional phrases. Singular subject "one" demands singular verb "has" regardless of plural elements in phrases like "of the students" that merely describe the subject group.