Which of the following is correct with regard to the grapevine?

Which of the following is correct with regard to the grapevine?
A) The grapevine is an early warning system, so managers should pay attention to it.
B) Managers cannot have an influence on the information carried by the grapevine because it is controlled by the informal organization.
C) Managers can eliminate the grapevine, but it takes a lot of time and effort to do so.
D) All things considered, it is best for the manager to ignore the grapevine because the accuracy of the information it carries is inconsistent and unpredictable.
E) All of these are correct.