請依下文回答第 41 題至第 45 題：
Ken Aston is an internationally known soccer referee. He came from England. Aston began playing soccer when he was a young boy. In 1936, when he was 19 years old, he hurt his ankle and stopped playing soccer. He decided to become a referee and qualified as one in the same year. In 1946, he became the first referee to wear the black uniform with white trim that later became the standard for referees.
As a soccer referee, Aston made an important contribution to the sport. He invented the card system. In modern soccer competitions, referees give cards to players who break rules. A yellow card is a warning. A red card means that the player is out of the game. According to Aston, the card system prevents language problems. The cards are an international language. Every player understands what the yellow and red cards mean.
Aston said he got the idea while stopping at a traffic light. He was driving home from a 1966 World Cup match. In that game, a German-speaking referee didn’t make his disciplinary calls clear. Some of the players could not understand him and had confusion in mind even after the game. So Aston came up with and pushed for the idea of showing a yellow card for an official warning and a red card for an ejection. The card system was introduced at the 1970 World Cup finals and are now used universally. Today all soccer players understand the meaning of the cards.
【題組】41 What is this passage mainly about?
(A)The history of soccer.
(B)Ken Aston’s career and contribution.
(C)How Aston got the idea for the card system.
(D)The meaning of a red or yellow card in soccer.