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: Frank was a school teacher. Sentence 2: He was just assigned a new classroom. Sentence 3: He went over to view his new place of work. Sentence 4: He found it to be very dirty. Sentence 5: He spent all evening cleaning it as best he could. Choices: a. bullet proof. b. Classroom.

b