Final answer:
Gatsby's reaction to seeing Daisy and Tom's daughter is one of surprise and disappointment, symbolizing his unfulfilled dreams.
Step-by-step explanation:
Gatsby's reaction to seeing Daisy and Tom's daughter is surprise and disappointment, symbolizing his unfulfilled dreams. This reaction shows that Gatsby had romanticized his relationship with Daisy and had high hopes for their future together. However, seeing Daisy with her family reminds Gatsby of the reality that he will never truly be a part of that world.