The town of Enderton is located in an area where forest fires are quite common. During dry periods and periods of persistent winds, when even a spark can result in a fire that spreads over many acres, the danger of fire there is particularly serious. To help prevent forest fires in the area, the town government plans to post a ban on outdoor fires when such conditions prevail.

Which of the following, if true, provides the strongest indication that the town's plan will have at most a minor effect on the annual number of forest fires in the Enderton area?

【选项】Nearly all forest fires in the Enderton area are the result of lightning strikes.