Answer: D
Explanation: Maintaining a watch for at least a half hour after completion of welding operations is not a responsibility of a fire watch.
A fire watch has the responsibility of detecting fires early so that they can be extinguished quickly thus preventing or minimizing damages to land and property. They are familiar with alarms systems and procedures, maintaining fire fighting equipment and also trained in their use.
Fire watches are often employed in forested areas with risk of fires (high) or in industrial settings where hot work is occurring such as welding or metal grinding.