Question

while species in the sunflower family typically present radial symmetry, where each petal grows in virtually identical form from a central axis, hong ma-a prominent researcher in the reproductive development and evolution of ______ led a study that indicated bilateral symmetry has emerged in some sunflower plants through convergent evolution.

which choice completes the text so that it conforms to the conventions of standard english?

choose 1 answer:
a plants, who
b plants-who
c plants;
d plants-

Explanation:

Analyze sentence structure

The sentence contains an appositive phrase describing Hong Ma: "a prominent researcher in the reproductive development and evolution of plants." This nonessential descriptive phrase is inserted directly after the subject "Hong Ma" and before the main verb "led."

Identify punctuation pattern

Using the Appositive Phrases knowledge point, nonessential parenthetical elements must be set off from the rest of the sentence with matching punctuation marks on both sides. Here, the appositive begins with an em dash: "Hong Ma—a prominent researcher...". Therefore, it must end with a matching em dash after "plants" to close the parenthetical insertion before the verb "led."

Evaluate the choices

Using the Punctuation Rules knowledge point, we test each option:

• (A) "plants, who" creates an unmatched pair of punctuation (dash at the start, comma at the end) and introduces an unnecessary relative pronoun "who" that leaves the verb "led" without its proper subject.
• (B) "plants—who" correctly closes the dash but incorrectly adds the relative pronoun "who," which disrupts the grammatical connection to the verb "led."
• (C) "plants;" uses a semicolon, which is incorrect because it does not match the opening em dash and is used to separate independent clauses.
• (D) "plants—" correctly closes the parenthetical appositive phrase with a matching em dash, allowing the subject "Hong Ma" to connect directly to the verb "led."

Answer:

• (A) plants, who
• (B) plants—who
• (C) plants;
• (D) plants— (Correct answer)