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Question

Difficulty: MediumEnd-of-Sentence Punctuation

In 1964, radio astronomers Arno Penzias and Robert Wilson detected a persistent background hiss that they could not explain, they initially suspected that the noise was caused by nesting pigeons. However, even after cleaning the antenna, the signal remained. This mysterious hum was actually the cosmic microwave background radiation, which is the remnant heat of the Big Bang.

Which of the following is the best choice for the underlined portion of the passage?

  1. A
    NO CHANGE
  2. explain. TheyAnswer
  3. C
    explain; although they
  4. D
    explain. Because they

Answer

The correct option separates the two independent clauses into two distinct sentences using a period: 'explain. They'
The correct option correctly uses a period to separate two independent clauses into two distinct sentences. Both 'In 1964, radio astronomers Arno Penzias and Robert Wilson detected a persistent background hiss that they could not explain' and 'They initially suspected that the noise was caused by nesting pigeons' are complete thoughts with their own subjects and verbs.

Step-by-Step Solution

1
Identify the clauses surrounding the underlined portion.
The clause before the underline is 'In 1964, radio astronomers Arno Penzias and Robert Wilson detected a persistent background hiss that they could not explain' and the clause after is 'they initially suspected that the noise was caused by nesting pigeons'.
To determine correct punctuation, you must first verify whether the clauses are independent or dependent.
2
Determine if each clause can stand alone as a complete sentence.
Both clauses contain a subject and a verb and express a complete thought, meaning they are both independent clauses.
Understanding clause type guides which punctuation marks are grammatically acceptable.
3
Select the punctuation that correctly separates these two independent clauses.
A period correctly separates the two clauses into two complete sentences.
Joining two independent clauses with only a comma creates a comma splice, while options containing subordinating conjunctions ('although' or 'because') turn the second clause into an ungrammatical sentence fragment.

Key Concept

End-of-Sentence Punctuation
Estimated Time:1m 0s
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Topics

End-of-Sentence Punctuation

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