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: Today was street cleaning day in Cambridge. Sentence 2: We woke up to watch cars being towed. Sentence 3: There were only two cars today. Sentence 4: One was towed, but the other was not. Sentence 5: We were mystified. Choices: a. Rollsign. b. Towing Day.

b