Ty Runt Has Always Taken a Hard Line Against Unionization

Ty Runt has always taken a hard line against unionization efforts. Two years ago, when workers at his previous company tried to obtain union representation, the company closed down the plant and refused to let employees work until they abandoned their efforts to form a union. This management tactic is called a(n)

A) management strike.
B) secondary boycott.
C) injunction.
D) lockout.