Extract:
What punctuation is needed in the following sentence to make it correct?
Because of a major accident on the freeway the emergency room was overcrowded.
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A
Period
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B
Comma
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C
Exclamation point
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D
Semicolon
A comma is needed after "Because of a major accident on the freeway" to separate the introductory dependent clause from the independent main clause.
A) Period
A period would terminate the dependent clause prematurely, creating a fragment followed by an ungrammatical main clause lacking proper connection.
B) Comma
Comma correctly separates the lengthy introductory prepositional phrase functioning as adverbial modifier from the independent clause "the emergency room was overcrowded." Standard grammar requires this comma for phrases exceeding four words.
C) Exclamation point
Exclamation points express strong emotion or emphasis—not clause separation. Using one here would create inappropriate emotional tone and fail to connect the clauses grammatically.
D) Semicolon
Semicolons connect independent clauses—not dependent phrases followed by independent clauses. The introductory element lacks subject-verb pair required for independent clause status.
Conclusion
Introductory phrases exceeding four words require commas before main clauses to create proper syntactic separation and enhance readability. Only a comma provides grammatically standard punctuation for this sentence structure with a lengthy prepositional phrase modifier.