Which tool can be used to unscrew a lock cylinder?

The correct choice is a tool specifically designed for gripping and turning objects, which makes it suitable for unscrewing a lock cylinder. In this context, vise grips are particularly effective because they can securely clamp onto the cylindrical surface of the lock, allowing a firefighter or technician to apply the necessary torque to turn and unscrew it. Vise grips can adapt to various sizes and provide a strong grip, which is essential when dealing with secure or rusted components.

While other tools may seem conducive for this task, they lack the same versatility and gripping power. For example, a key tool is typically used to manipulate specific locking mechanisms rather than applying torque to unscrew. A chain whip, often used in plumbing or bike repair, operates differently and is not suited for this application. Similarly, a strap wrench is designed to grip fragile surfaces and may not provide the needed leverage for unscrewing a lock cylinder effectively. Thus, vise grips are the preferred choice for this particular job.