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: My dog has gained some extra weight. Sentence 2: I've been trying to take him for a walk every day. Sentence 3: He's too small to walk for long. Sentence 4: I end up having to carry him home. Sentence 5: At least I'll lose some weight. Choices: a. Heart Beat. b. A walk.

b