Automatic system actuation valves for spray systems can be actuated electrically by the operation of automatic detection equipment, such as:
1. Heat detectors.
2. Relay circuits.
3. Gas detectors.
4. Mechanically.
a. 1, 2
b. 2, 3
c. 3, 4
d. 1, 2, 3
e. 1, 2, 3, 4.
Answer: E