What is it called when employees protest by refusing to work?

The action described when employees protest by refusing to work is termed "going on strike." This is a collective action taken by workers to express dissatisfaction with their working conditions or to demand changes such as better pay, working hours, or safety conditions. During a strike, employees withhold their labor as a means to exert pressure on their employer, often as part of a larger negotiation or labor dispute.

The other choices do not encapsulate the concept of employees collectively refusing to work. "Taking leave" typically refers to an individual employee taking time off from work for personal or medical reasons and does not signify a protest or collective action. "Filing a grievance" involves lodging a formal complaint about workplace issues, addressing specific concerns through established procedures, rather than outright refusal to work. "Requesting a meeting" is a proactive approach to discuss issues but does not represent a protest and does not reflect the assertive action of withholding labor. Thus, "going on strike" is the most accurate term for the described action.