Which of the following actions is illegal for a player during a match?

In volleyball, certain actions during a match are considered illegal as they can affect gameplay or the safety of players. Grasping the standards for support is frowned upon because it can disrupt play and is not allowed during a rally. Falling into the net is illegal as it can interfere with the match; players must avoid contact with the net during play. Similarly, holding onto the referee's platform for support is also against the rules, as it can interfere with the officiating process and creates an unfair advantage.

Each of these actions compromises fair play, which is why they are categorized as illegal during a match. Therefore, it is accurate to state that all the mentioned actions are illegal, highlighting the importance of adhering to the regulations to ensure a safe and fair environment for all players involved.