Instructions: 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 officer opened up the jail cell since it was lunch time. Sentence 2: Rex saw a moment to run away. Sentence 3: He started to run after the officer looked away. Sentence 4: Several officers on the other side grouped together. Sentence 5: They managed to take Rex down and put him inside of his cell. Choices: a. Moment to Break Free. b. The Stain.
Output:
a