【答案解析】由“Fans get angry if they feel that a referee has made a wrong decision，perhaps giving one of their team a red or yellow card unfairly，or perhaps failing to notice a foul(犯规) committed by a member of the other team．”可知，当球迷发现裁判错判或未能发现另一 队的球员犯规时会很生气。故答案为A。