Questions: Question 21 (2 points). A type of fire sprinkler system where all the sprinkler heads become activated when fire is detected in even just one location is a system. 1) wet-pipe system 2) dry-pipe system 3) deluge system 4) antifreeze system

The answer is the third one (3): deluge system.

Explanation for each option:

1. Wet-pipe system: This type of system has water in the pipes at all times, and only the sprinkler heads directly exposed to heat from a fire will activate. Therefore, it does not fit the description given in the question.
2. Dry-pipe system: This system has air or nitrogen in the pipes, and water is released into the pipes only when a sprinkler head is activated by heat. Similar to the wet-pipe system, only the sprinkler heads exposed to heat will activate, so it does not match the description.
3. Deluge system: This system has open sprinkler heads, and when a fire is detected, a valve opens to allow water to flow through all the sprinkler heads simultaneously. This matches the description given in the question, where all sprinkler heads become activated when fire is detected in even just one location.
4. Antifreeze system: This system uses a solution of water and antifreeze in the pipes to prevent freezing in cold environments. It operates similarly to wet-pipe or dry-pipe systems, where only the sprinkler heads exposed to heat will activate. Therefore, it does not fit the description given in the question.

Summary: The correct answer is the third one (3): deluge system. This type of fire sprinkler system activates all sprinkler heads when fire is detected in any location.