Answer:
C)
Explanation:
A) is about politeness, you don't want a phone to ring in the gym. It has nothing to do with safety, as it is very u likely to knock someone off a treadmill. It's just annoying.
B) is about cleanliness. No one wants to work out in someone else's sweat. This does not have to do with safety.
C) To avoid possible accidents, hikers walk in the middle of the trail. This keeps them safe.
D) is about politeness, again. In fact, it might be safety to say something when passing another runner, so they know that you're there and not knock into you.
C) is the only rule relating to safety
