In the 1940s, geneticist Barbara McClintock conducted pioneering research on the inheritance patterns of maize plants. Her work focused on transposons ______ which challenged the prevailing scientific consensus that genomes are rigid and unchanging. Although her findings were initially met with skepticism from the scientific community, McClintock's discoveries eventually earned her a Nobel Prize in 1983.
Which choice completes the text so that it conforms to the conventions of Standard English?
- A, genetic elements that can move to different positions within a genome—
- B—genetic elements that can move to different positions within a genome,
- —genetic elements that can move to different positions within a genome—Answer
- D, genetic elements that can move to different positions within a genome
Answer
The choice that begins and ends the appositive phrase with matching em dashes is correct.
The correct choice uses a pair of matching em dashes to set off the nonessential appositive phrase 'genetic elements that can move to different positions within a genome'. In English grammar, nonessential elements must be set off from the rest of the sentence using matching punctuation marks, such as two commas, two em dashes, or parentheses.
Step-by-Step Solution
Key Concept
Punctuation of Nonessential Elements
Estimated Time:1m 0s