Which of the following is a term for a labor-dispute tactic used by neither unions nor management?

The correct response is "seizure," as it refers to a situation where an outside party, typically the government, takes control of a business or industry during a labor dispute, without involvement from either the unions or management. This tactic is often employed in cases of national interest where a strike or lockout severely affects public services or critical industries, such as during wartime or in essential service sectors.

In contrast, the other terms relate directly to tactics employed either by unions or management to address disputes. A boycott involves a union encouraging the public to avoid a company’s products or services as a way to exert pressure. Mediation is a process where an impartial third party assists in negotiating between the conflicting parties to reach a solution, and arbitration is a more formal method where a third party makes a binding decision after hearing from both sides. These methods are all direct strategies used by the parties involved in labor disputes, distinguishing them from seizure, which operates outside the direct control or tactics of the disputing parties.