Which of the following statements is true of a union shop?

a. It requires workers to join the union, usually 30 to 60 days after being hired.
b. It requires job applicants to have a union card to be considered for employment.
c. It requires workers who refuse to join the union to pay a special fee to get union representation services.
d. It requires a union to represent all employees in a company, including nonmembers of the union.