Final answer:
The confrontation between Gatsby and Tom reveals the most about Nick's relationship with Gatsby.
Step-by-step explanation:
The event from The Great Gatsby that reveals the most about Nick's relationship with Gatsby is the confrontation between Gatsby and Tom. In this scene, Nick witnesses the clash between Gatsby and Tom over Daisy, which exposes Gatsby's deep love for her and his willingness to fight for her. It also shows Nick's loyalty to Gatsby as he stands by him during the confrontation.