Detailed Instructions: 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'.
Q: Sentence 1: I decided to try doing jumping jacks for exercise. Sentence 2: I started doing them first thing in the morning. Sentence 3: I could only do twenty before I felt like I was dying. Sentence 4: I eventually built my tolerance to about fifty per day. Sentence 5: I started to lose a little weight because of it. Choices: a. Jumping. b. The dog.
A:
a