Mount Everest ______ which is more than five miles above sea level, presents extreme physiological challenges to even the most experienced mountaineers.
Which choice completes the text so that it conforms to the conventions of Standard English?
- Acheck_circle
,
- B
;
- C
(empty)
- D
:
Explanation
Mount Everest is uniquely identified, so "which is more than five miles above sea level" is nonrestrictive and must be set off by paired commas; the closing comma already exists.