Which of the Following Violates the Principle of Just Cause

Which of the following violates the principle of just cause?

A) A company launches a criminal investigation into allegations that an employee has been intentionally making mistakes in his work to "get back at" his supervisor.
B) David is disciplined because a co-worker, Bonita, tells their supervisor that David has been making personal long-distance calls on company telephones.
C) Employees are notified by their supervisor that they will be disciplined if they leave work before an important job is finished that day.
D) Seth has been with his employer for two years and has a perfect service record. Today, however, his supervisor saw him use a tool unsafely on the shop floor. The supervisor briefly chats with Seth about proper use of tools.