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: The man locked the door. Sentence 2: His son came home. Sentence 3: He had forgot his key. Sentence 4: He knocked on the door. Sentence 5: His dad admonished him for not having the key. Choices: a. Taking a Friend Shopping. b. Key.

b