The glacier's slow but inexorable retreat ______ documented in photographs spanning over a hundred years ______ provides stark visual evidence of climate change.
Which choice completes the text so that it conforms to the conventions of Standard English?
- A
(, )
- Bcheck_circle
—, —
- C
, —
- D
—,
Explanation
A pair of em-dashes properly sets off a parenthetical for emphasis. Mismatched punctuation is ungrammatical.