Answer
Tosylate is a better leaving group.
** This group is illustrated on the top of the page 219, in the sulfonate ions table.
Work Step by Step
1. Identify the possibles leaving groups:
- $Tosylate$
- $NH_2^-$
2. Determine which one is better.
- In this section, we've learned that sulfonate ions, like tosylate, are good leaving groups (page 219).
- And we have also learned that $NH_2^-$ is a bad leaving group (page 218).
Therefore, this tosylate is better.