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: Sam went for a jog one evening. Sentence 2: He wasn't used to exercise, so he got tired quite quickly. Sentence 3: At first, he wasn't even able to run a block without stopping. Sentence 4: Only 2 months later, Sam is preparing to run a marathon. Sentence 5: His health has benefited from staying motivated each day. Choices: a. The Big Game. b. No pain no gain.

b