Sleep apnea IS a serious sleep disorder, in which people:

A) Walk during sleep without knowing what he or she is doing.

B) Sleep with eyelids half open.

C) Briefly and repeatedly stop breathing during sleep.

D) Make loud snoring sound while a sleep.

This MCQ is part of the UP PSC Previous Year Questions (PYQs) series, focusing on UPPSC Prelims 2014 (GS Paper I)