Heat waves are periods of excessively hot and dry weather. In areas of prolonged drought, heat waves can cause wild fires and destroy vegetation. What tactic is essential in preventing wild fires from occurring?
A) Cut down all the vegetation in the area.
B) Ask all people in drought-hit areas to vacate.
C) Supply water to the drought-hit areas in case of fires.
D) Closely monitor and immediately extinguish small fires.