What does that sign mean?

giúp mik vs ạ
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15. What does that sign mean?
WATCH YOUR STEP
A. Be careful! People are watching your step.
B. You have to look at the way you step.
C. You should be careful when you are walking.
D. You have to look at your feet when you are walking.
16. What does this sign mean?
SCHOOL
SPEED
LIMIT
15
7AM TO 6PM
SCHOOL DAYS
A. You must drive faster than 15km/h in the school zone.
B. Students should be at school from 7 a.m. to 6 p.m.
C. The speed limit is not for weekends.
D. Students shouldn't drive on school days.