Final answer:
The true statement about Daylight Saving Time (DST) is that it is used to extend the hours of daylight during the summer months, by setting the clock forward one hour. It does not save actual daylight nor is it observed by all countries globally, and it doesn't alter the natural length of a day.
Step-by-step explanation:
The question regarding which of the following statements is true about Daylight Saving Time (DST) has a clear answer. The correct statement is A) It is used to extend the hours of daylight during the summer. Daylight saving time involves setting the clock forward by one hour during the warmer part of the year, so that evenings have more daylight and mornings have less. Most areas of the United States and many other countries worldwide observe DST, adjusting the time to extend daylight into the evening hours.
Contrary to some misconceptions, Daylight Saving Time does not actually 'save' or alter the amount of daylight that occurs, as this is determined by the Earth's position relative to the Sun. Also, it is not true that DST is observed in all countries worldwide nor does it result in a 24-hour day; the length of a day remains based on the Earth's rotation, which is not affected by changes in local time keeping. Last but not least, DST predates World War II, having been first used in Germany during World War I to conserve coal.