A Union Representing a Group of Workers Will Tend to Be

A union representing a group of workers will tend to be stronger when

A) there are no good substitutes for the labor services of the unionized workers.
B) the domestic producers of the good produced by the unionized workers face intense competition from foreign suppliers of the good.
C) the cost of employing the unionized workers is a large part of the total cost of the product that they produce.
D) the demand for the good produced by the unionized workers is highly elastic.