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: The man threatened to kill his enemy. Sentence 2: His enemy took this seriously. Sentence 3: His enemy killed him. Sentence 4: His enemy felt bad. Sentence 5: His enemy left a sympathetic note. Choices: a. kill. b. Suburbs.

a