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: Mark had bought a new car. Sentence 2: Within a week, the car developed engine trouble. Sentence 3: The car was still under warrantee. Sentence 4: Mark brought the car back to the dealership. Sentence 5: The dealership allowed him to exchange the car. Choices: a. New Neighbors. b. Lemon.

b