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: An air conditioner fell in the office. Sentence 2: Several objects started to fall afterwards. Sentence 3: Everyone had to evacuate the building after an announcement. Sentence 4: The office was relocated since the building was deteriorating. Sentence 5: We didn't return into next year. Choices: a. Collapse. b. Robert gets a ticket.

a