Which of the Following Would Be an Example of an Implicit

Which of the following would be an example of an implicit norm in an information technology group?

A) a rule that a meeting cannot occur unless at least 50 percent of the members are present
B) the use of PowerPoint by everyone when they make presentations
C) using Roberts Rules of Order to conduct all business in the group
D) a requirement that agenda items be submitted at least 24 hours before the meeting