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Question

Difficulty: EasyPunctuation of Nonessential Elements

The passage below contains a blank where a punctuation mark is missing. What is the single punctuation mark that must fill the blank to make the sentence grammatically correct?

Answer:In the mid-twentieth century, concerns about industrial pollution and pesticide overuse began to influence public policy. Marine biologist Rachel Carson—who published the influential book *Silent Spring* in 1962【—】is widely credited with launching the modern environmental movement. By describing the detrimental effects of chemical pesticides on ecosystems, her work challenged the prevailing belief that humans could control nature without consequences and inspired subsequent conservation efforts.

Answer

An em dash (—) is the correct punctuation mark to fill the blank.
The sentence contains a nonessential relative clause, 'who published the influential book *Silent Spring* in 1962,' which provides extra details about Rachel Carson. Because this clause is introduced with an em dash (—), it must be closed with a matching em dash to maintain punctuation symmetry.

Step-by-Step Solution

1
Identify the nonessential element in the sentence.
The clause 'who published the influential book *Silent Spring* in 1962' is a nonessential relative clause because removing it does not change the core meaning of the main sentence.
Recognizing the boundaries of the nonessential clause helps determine where the punctuation marks must be placed.
2
Examine the punctuation mark that opens the nonessential element.
The clause is introduced with an em dash ('—').
Nonessential elements must be set off by matching pairs of punctuation marks.
3
Determine the correct matching punctuation mark to close the clause.
To match the opening em dash, an em dash ('—') must be placed at the end of the clause after '1962'.
Punctuation marks setting off a nonessential element must be symmetrical (e.g., two commas, two dashes, or a pair of parentheses). Mixing different types of punctuation, such as starting with a dash and ending with a comma, is grammatically incorrect.

Key Concept

Punctuation of Nonessential Elements
Estimated Time:45s
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Topics

Punctuation of Nonessential Elements

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