Do you know the game "Rock, paper or scissors"? Maybe you think it's just a simple game for children. But in fact, some adults use it to make decisions and solve their problems. It is also popular in many countries. There are different stories about the history of the game. But many people believe the game  came from Japan, and Japanese have played it for a long time. Later it came to Europe in the middle of the 18th century. In 1842, England founded the Paper Scissors Stone Club and from then on people could get together to play the game for honor  . There is even an international club named the World Rock Paper Scissors Club in Toronto. The club makes "Rock, paper or scissors" more and more popular. It holds the world championship   every year. Top players from around the world take part in it and the champion   can get a lot of money and the honor of all the fans of "Rock, paper or scissors". How often does the World Rock Paper Scissors Club hold the world championship?
Once a year. Once two years. Once three years. Once four years.