Which of the Following Statements Describes the "Rand Formula

Which of the following statements describes the "Rand Formula"?

A) It is used to determine what percentage of an employee's earnings can be deducted for union membership dues.
B) It identifies the public sectors in which workers are not allowed to strike because of the percentage of citizens who might be negatively affected.
C) It requires employers to deduct union dues from all employees in a workplace that is unionized, whether or not they belong to the union.
D) It is used to determine whether or not an international union can be forced to allow Canadian workers to set up their own union.