Students _______ have completed the prerequisite courses may register for advanced seminars.
2
readingWhich choice completes the text so that it conforms to the conventions of Standard English?
A
who have completed the prerequisite courses
B
, who have completed the prerequisite courses,
C
, who have completed the prerequisite courses
D
who have completed the prerequisite courses,
Correct Answer: A
Choice A is the best answer. This question tests essential vs. nonessential clauses.
- Context clues: The clause identifies WHICH students may register—essential.
- Meaning: Essential clauses are NOT set off by commas.
- Verify: "Students who have completed the prerequisite courses may register" specifies which students.
💡 Strategy: Essential clauses (identifying who/what) take no commas.
Choice B is incorrect because commas make it nonessential. Choice C is incorrect because one comma is grammatically inconsistent. Choice D is incorrect because one comma after is grammatically incorrect.