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: Bella is taking a college level US history course. Sentence 2: She had to do a paper on the US history between 1865 and today. Sentence 3: She wrote on the development and use of atomic bombs in war. Sentence 4: She learned that her grandfather's could have died invading Japan. Sentence 5: So she probably would not have been born without the bombs. Choices: a. History Assignment. b. Low Clearance.

a