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: Ken wanted to mail his sweetheart a love letter. Sentence 2: Ken spent days writing the perfect letter. Sentence 3: He went to give it to the postman to put it in his sack. Sentence 4: A few days later his letter came back. Sentence 5: It had the message Return to sender written on it. Choices: a. Return to sender. b. Ronnie sees a bear.

a