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: Historians debated history. Sentence 2: They had different opinions. Sentence 3: They had similar timelines, however. Sentence 4: They made one master timeline of events. Sentence 5: They got famous for this. Choices: a. Nature Fighting Back. b. Timeline.

b