Final answer:
Stored-pressure water mist extinguishers are safe and effective for Class A and Class C fires, but not for Class B fires, combustible metal fires, or combustible cooking oil fires due to the potential to spread the flammable materials and ineffectiveness on high temperatures. Correct answer is d. Class C.
Step-by-step explanation:
Stored-pressure water mist extinguishers are designed to be safe and effective for use on certain types of fires. Specifically, stored-pressure water mist extinguishers can be used on Class A fires, which involve common combustibles such as wood, paper, and cloth. They can also be effective on Class C fires, which involve electrical equipment, as the water mist does not conduct electricity, and it can help in cooling down the equipment and reducing the heat.
However, they are not suitable for Class B fires that involve flammable liquids or gases, nor are they recommended for combustible metal fires or combustible cooking oil fires (like in deep fat fryers). This is because the water mist can spread the flammable liquids, potentially making the fire worse, and it is not effective on the high temperatures of metal and cooking oil fires. Therefore the correct answer is d. Class C.