選手 and 審判: roles in a sporting event
Distinguish players from referees and track who makes a ruling or receives an explanation.
The player or athlete
選手, read せんしゅ, means player or athlete. 選手が会場に入りました。 says that an athlete entered the venue.
選手に質問しました。 means asking an athlete a question. Do not reverse the actor into the athlete asking.
The referee
審判, read しんぱん, can refer to an official or officiating. 審判が試合を止めました。 says that the referee stopped the match.
審判の説明を聞きました。 means listening to the referee's explanation. It does not mean explaining something to the referee.
Changing roles
以前は選手でしたが、今は審判です。 says that the person used to be an athlete and is now a referee. Distinguish the past role from the current one.
選手が審判に理由を尋ねました。 says that the player asked the referee for the reason. が and に distinguish the asker from the recipient.
Who asked for the reason in 選手が審判に理由を尋ねました?
Show the answer and why
The player. The referee received the question.