In a 2023 study, researchers documented a fascinating behavior in the aquatic plant Elodea densa. When exposed to low levels of light, the plant's ________ the cellular organs that generate energy from light — reshuffled to form a tightly packed, glass-like surface ideal for collecting more light.
Which choice completes the text so that it conforms to the conventions of Standard English?
Explanation
Context: "When exposed to low levels of light, the plant's chloroplasts — the cellular organs that generate energy from light — reshuffled to form a tightly packed, glass-like surface." Paired em-dashes enclose the definition of "chloroplasts."
Answer: B) chloroplasts —
Why? An em-dash after "chloroplasts" opens the parenthetical definition "— the cellular organs that generate energy from light —" which is closed by another em-dash before "reshuffled."
Traps:
- A) "chloroplasts," → comma opens the definition but the sentence closes with a dash — mismatched marks
- C) "chloroplasts" → without the opening dash, the parenthetical definition isn't properly set off
- D) "chloroplasts;" → a semicolon doesn't open a parenthetical phrase