A、India. B、Turkey. C、France. D、Germany. C讲座中提到，罗马教皇格利高里十三世于1582年下令用新的日历替换旧的罗马儒略历，新日历提倡在1月1日庆祝新年。同年，法国采用了改革后的日历，将新年定在1月1日。因此答案为C)

April Fools’ Day, sometimes called All Fools’ Day, is one of the most light-hearted days of the year. Its origins are uncertain. Some see it as a celebration related to the turn of the seasons, while others believe it stems from the adoption of a new calendar.
    Ancient cultures, including those of the Romans and Hindus, celebrated New Year’s Day on or around April 1.In medieval times, much of Europe celebrated March 25 as the beginning of the new year.
    In 1582, Pope Gregory XI ordered a new calendar to replace the old Julian calendar. The new calendar called for New Year’s Day to be celebrated on January 1.That year, France adopted the reformed calendar and shifted New Year’s Day to January 1.According to a popular explanation, many people either refused to accept the new date or did not learn about it and continued to celebrate New Year’s Day on April 1.Other people began to make fun of these traditionalists, sending them on "fool’s errands" or trying to trick them into believing something false. Eventually, the practice spread throughout Europe.
    Another explanation of the origins of April Fools’ Day was provided by Joseph Boskin, a professor of history at Boston University. He explained that the practice began during the reign of Constantine, when a group of court jesters and fools told the Roman emperor that they could do a better job of running the empire. Constantine, amused, allowed a jester named Kugel to be the king for one day. Kugel passed an edict calling for absurdity on that day, and the custom became an annual event.
    "In a way," explained Prof. Boskin, "it was a very serious day. In those times, fools were really wise men. It was the role of jesters to put things in perspective with humor. "
    This explanation was brought to the public’s attention in an Associated Press article printed by many newspapers in 1983.There was only one catch; Boskin made the whole thing up. It took a couple of weeks for the AP to realize that they’d been victims of an April Fools’ joke themselves.
    It is worth noting that many different cultures have had days of foolishness around the start of April, give or take a couple of weeks. The Romans had a festival named Hilaria on March 25, rejoicing in the resurrection of Attis. The Hindu calendar has Holi, and the Jewish calendar has Purim. perhaps there’s something about the time of year, with its turn from winter to spring, that lends itself to light-hearted celebrations.
    Questions 19 to 22 are based on the recording you have just heard.
    19.Which country adopted the new calendar ordered by Pope Gregory XI in 1582?
    20. What does the first popular explanation say about April Fool’s Day?
    21.What can we learn about the explanation from Prof. Boskin about the origin of April Fools’ Day?
    22.Why do so many cultures celebrate days of foolishness around the start of April?