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Question

Difficulty: MediumRun-on Sentences and Comma Splices

Read the following passage and consider the underlined portion:

Palynologists analyzing sediment cores from subarctic peat bogs can reconstruct ancient climate conditions. By cataloging fossilized pollen grains preserved in oxygen-poor soil layers, researchers map shifting forest boundaries over millennia, however, sudden temperature fluctuations often disrupt local plant migration patterns.

Which of the following alternatives to the underlined portion is grammatically correct?

  1. A
    NO CHANGE
  2. researchers map shifting forest boundaries over millennia; however, sudden temperatureAnswer
  3. C
    researchers map shifting forest boundaries over millennia, however sudden temperature
  4. D
    researchers map shifting forest boundaries over millennia; however, because sudden temperature

Answer

The correct option replaces the underlined text with 'researchers map shifting forest boundaries over millennia; however, sudden temperature', using a semicolon before the conjunctive adverb and a comma after it to connect two complete independent clauses.
The correct choice places a semicolon before the conjunctive adverb 'however' and a comma after it. Because both 'researchers map shifting forest boundaries over millennia' and 'sudden temperature fluctuations often disrupt local plant migration patterns' are independent clauses, a semicolon is required to separate them when joined by a transitional adverb.

Step-by-Step Solution

1
Identify the structure of the two clauses surrounding the underlined transition.
The clause before 'however' ('By cataloging fossilized pollen grains preserved in oxygen-poor soil layers, researchers map shifting forest boundaries over millennia') and the clause after ('sudden temperature fluctuations often disrupt local plant migration patterns') are both independent clauses capable of standing alone as complete sentences.
Recognizing independent clauses determines the required punctuation for compound sentences.
2
Evaluate the grammatical rules for connecting independent clauses with conjunctive adverbs like 'however'.
A conjunctive adverb connecting two independent clauses must be preceded by a semicolon (or a period) and followed by a comma. A comma alone creates a comma splice.
Conjunctive adverbs are not coordinating conjunctions (FANBOYS) and cannot join independent clauses with only a comma.
3
Select the option that applies the correct punctuation without introducing new errors.
The phrasing with a semicolon before 'however' and a comma immediately following it properly connects the clauses while maintaining grammatical accuracy.
This resolves the comma splice while preserving the logical contrast between long-term mapping and sudden climate disruptions.

Key Concept

Correcting Comma Splices with Conjunctive Adverbs
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Topics

Run-on Sentences and Comma Splices

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