Which of the following would be an example of the mum effect?

a$.$

The president of a university refused to tell a newspaper reporter specific numbers related to their international student enrollement

b$.$

The manager would only communicate with employees through their immediate supervisors

c$.$

During lunch, a colleague was sitting with employees who were gossiping, but refused to participate in the discussion

d$.$

A consultant within a medium sized consulting firm delayed telling his senior directors that he had just lost a significant client

e$.$

The sales manager waited until the annual Christmas party to announce that all employees would be receiving a huge bonus!