Answer:
D. Phone numbers of parents
Step-by-step explanation:
Phone numbers of parents are important, but they shouldn't be posted on the school calendar. Especially for safety reasons. Everything else is appropriate because they are important events that should be posted in case someone forgot. Calendars are for reminding what would happen on a certain day ahead of time, in case it is forgotten. Parents phone numbers aren't events nor should they be posted. Therefore the answer would be D. Phone numbers of parents.
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