We recognize that peaceful industry is necessary to successful civilized life, but the right to strike and the preparation to strike is the greatest preventive to strikes. If the workmen were to make up their minds tomorrow that they would under no circumstances strike, the employers would do all the striking for them in the way of lesser wages, and longer hours of labor."
—Report on the (U.S.) Industrial Commission on Capital and Labor, 1890

In this report, Samuel Gompers is explaining the need for

A. wage labor.
B. freedom of contract.
C. pensions.
D. unions.

Samuel Gompers is known in American history as a foremost leader in the establishment of labor unions. He advocated for the establishment of unions that would fight for better wages and working conditions for its members.

Here, the passage can be interpreted to mean that without unions, employers would have free rein to do as they pleased without taking the welfare of workers into consideration.