Which of the following is an example of an employer unfair labor practice?

a. Chang Liu, a union member, terminates an existing contract and strikes for a new one without informing the employer.
b. Tamara Long, a nonunion employee, causes a member to include illegal provisions in a contract.
c. Diego Pantera, the union representative, causes threats of bodily injury to employees.
d. Amber Ryan, a worker, causes the discharge of an employee who spoke out against a contract proposed by the union.
e. Karla Johnstone, a supervisor, pretends to spy on union meetings.