Definition: In this task, you're given five sentences, numbered 1 through 5, and two options a and b for possible titles for the story. Your job is to choose the title that better fits the story. Indicate your choice by 'a' or 'b'.
Input: Sentence 1: Tom was a thrill junkie. Sentence 2: He decided to go skydiving. Sentence 3: The experience was exciting. Sentence 4: Tom did it dozens more times. Sentence 5: Eventually he became an instructor. Choices: a. Sky Diving. b. The tree.

a