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Question

Difficulty: HardColons

During a 1977 expedition in the Pacific Ocean, oceanographers aboard the research vessel *Alvin* discovered: hydrothermal vents teemed with life in the pitch-black depths, challenging the long-held belief that all food chains must begin with sunlight.

Which of the following choices best completes the underlined portion of the sentence?

  1. A
    NO CHANGE
  2. B
    discovery, hydrothermal vents teemed
  3. discovery: hydrothermal vents teemedAnswer
  4. D
    discovery. Hydrothermal vents teeming

Answer

The correct choice is the option that replaces the verb 'discovered' with the noun phrase 'made a startling discovery' followed by a colon.
The correct choice changes the verb 'discovered' to the noun phrase 'made a startling discovery' to form an independent clause before the colon. It also uses a colon to correctly introduce the second independent clause, which explains the discovery.

Step-by-Step Solution

1
Analyze the grammatical structure of the clause preceding the punctuation mark.
The original sentence uses 'discovered', which is a verb. A colon cannot immediately follow a verb because it leaves the preceding clause incomplete.
To use a colon, the preceding clause must be independent (able to stand alone as a complete sentence).
2
Evaluate the options that turn the preceding clause into an independent clause.
Replacing 'discovered' with 'made a startling discovery' creates an independent clause.
This establishes the necessary grammatical foundation for using a colon.
3
Examine the grammatical structure of the clause following the punctuation mark to ensure it is not left as a fragment if a period is used, or joined incorrectly if a comma is used.
The clause 'hydrothermal vents teemed with life...' is independent. Using a comma creates a comma splice, and using a period with the participle 'teeming' creates a fragment. Using a colon to connect the two independent clauses is correct because the second clause explains the first.
Colons can connect two independent clauses when the second clause illustrates or explains the first.

Key Concept

Use of colons to introduce explanation or amplification after an independent clause.
Estimated Time:1m 0s
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Topics

Colons

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