Basketball is an American game. The idea of inventing the basketball came from Dr. Luther Hal-sey Gulick, Jr. , P. E. teacher at the YMCA Training School. He thought that the students needed a new indoor game that would be interesting, easy to learn, and easy to play in the winter. It must be played by many players at a time and it should call for a lot of exercise. James Naismith, one of his students, invented the new game. The first real game was played in 1892. Naismith put up two peach (桃子) baskets. There were nine players on each side. They tried to throw the ball into the baskets. There were no holes at the bottom of the baskets. When a ball went into the basket, the game had to stop. A player climbed up to get the ball. It was a slow game. Later people used net(网状的) baskets. They cut the bottoms out of the baskets. The game quickly moved to other places. Many clubs, high schools and colleges began to have this game. By 1905, it was recognized as a permanent(永久性的) winter sport. At first, many persons could play. Now only ten members play the game. There are five players on each side. The passage is mainly about ______.
A. the basketball game B. the rules of the basketball game C. the number of the players in the basketball game