Final answer:
In ice hockey, the boarding penalty should be assessed to Player A1 since they initiated the dangerous play by pushing their teammate into the opponent, even though Player A2 was the one in direct contact.
Step-by-step explanation:
The question relates to a situation in ice hockey, where a player (Player A1) pushes a teammate (Player A2) into an opponent causing a dangerous situation that typically would warrant a boarding penalty. In such cases, the boarding penalty should be assessed to the player who initiates the dangerous contact, which is Player A1. Even though Player A2 was the one to ultimately make contact with the opponent, it was Player A1's action that caused the dangerous play. Thus, Player A1 is responsible for the boarding and should be given the penalty.