Daylight savings is a system of setting clocks 1 or 2 hours ahead. This causes sunrise and sunset to happen at a later hour. Daylight savings results in an extra hour of daylight in the evening. This idea was first jokingly mentioned in an essay by Benjamin Franklin in 1784. British builder William Willet wrote seriously about the idea in 1907.
Daylight savings has been used in the U. S. and many European countries since World War I. The system was started to conserve fuel needed to get electric power. Homes and businesses did not have to turn their lights on as early. Some places in the U. S. went back to standard time after the war.
During World War II, U. S. Congress passed a law putting the whole country on "war time." This set the clocks ahead 1 hour for the rest of the war. The Uniform Time Act in 1966 set up a daylight savings schedule for most of the U. S. Each state voted on whether the state would follow daylight savings time.

What is the main idea of this passage?
A.
the people who invented daylight savings time
B.
what daylight savings time is and why we use it
C.
how daylight savings time helps conserve fuel
D.
how to set the clocks for daylight savings time