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Difficulty: Very hardCommas with Nonessential and Parenthetical Elements

Before Alan Turing's famous work at Bletchley Park, a team of Polish mathematicians cracked the early military Enigma cipher. Marian Rejewski solved the mathematical equations underlying the machine's rotor permutations. The card catalog that Rejewski compiled during his research, which contained over 100,000 permutations, allowed the team to decrypt messages in minutes.

Which choice best punctuates the underlined portion of the sentence?

  1. NO CHANGEAnswer
  2. B
    , that Rejewski compiled during his research, which contained over 100,000 permutations, allowed
  3. C
    that Rejewski compiled during his research, which contained over 100,000 permutations allowed
  4. D
    that Rejewski compiled during his research; which contained over 100,000 permutations, allowed

Answer

The original phrasing, which leaves the restrictive clause unpunctuated and encloses the nonessential clause within commas, is correct.
The correct choice properly distinguishes between the restrictive clause 'that Rejewski compiled during his research' and the nonessential clause 'which contained over 100,000 permutations'. Because the 'that' clause is essential to defining the specific catalog, it requires no commas. The 'which' clause is nonessential, so it must be enclosed by a matched pair of commas—one before 'which' and one after 'permutations'—allowing the main subject 'The card catalog' to link to its verb 'allowed'.

Step-by-Step Solution

1
Identify the clauses modifying the noun 'card catalog' and determine if they are essential (restrictive) or nonessential (nonrestrictive).
The clause 'that Rejewski compiled during his research' is restrictive because it specifies which catalog is being discussed. The clause 'which contained over 100,000 permutations' is nonessential because it provides additional, non-identifying detail about the catalog.
Understanding the semantic role of each clause dictates the correct punctuation rules to apply.
2
Apply the punctuation rules for restrictive and nonessential clauses.
Do not place commas around the restrictive clause starting with 'that'. Place a pair of commas around the nonessential relative clause starting with 'which' to set it off from the rest of the sentence.
Restrictive clauses are essential to the sentence's meaning and must not be separated from their referent, whereas nonessential elements must be set off by a matched pair of commas.
3
Evaluate the choices to ensure no punctuation marks are misplaced or create grammatical fragments.
The original punctuation maintains the integrity of both clauses and allows the subject 'The card catalog' to connect smoothly to the verb 'allowed'. Alternatives introduce errors such as dangling commas, separated restrictive clauses, or a semicolon that cuts off a dependent clause.
This guarantees that the sentence remains grammatically complete and clear.

Key Concept

Commas with Nonessential and Parenthetical Elements
Estimated Time:1m 0s
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Topics

Commas with Nonessential and Parenthetical Elements

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