we did that and they still wanted to choose even to the point of arguing at half time. it was hugely painful.
Explaining penalty options is one of the prime responsibilities of the Referee. Despite, even what might be the most perfectly clear and concise explanation, the intended message, at times, may not be clearly understood. Much of any success of that communication depends on the age and maturity of the listener, and it's left to the skill of the explainor to be able to figure out how to convey the message so it's context is appropriately understood.
Sometimes it requires first outlining the functions of the participants in the discussion; The Referee's job is to explain, the Captain's (Coach) job is to listen. Until that's understood, communication can be difficult. Being able to differentiate between when someone may be honestly confused, or choosing to just be argumentative is a hard earned skill.