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: Allison bought herself a new treadmill. Sentence 2: She hopped on for the first time and started experimenting. Sentence 3: She kept going faster and faster on the treadmill. Sentence 4: Eventually, she couldn't run fast enough. Sentence 5: Allison fell off the back of the treadmill and slammed onto the floor. Choices: a. Exercising. b. Summer School.

a