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: Lindsey took out a knife and carved her name into the tree. Sentence 2: A park ranger came by and said that would kill the tree. Sentence 3: Lindsey felt terrible and kissed the tree. Sentence 4: She then bought a little sapling and planted it beside the large tree. Sentence 5: Years later, Lindsey returned and the sapling had grown into a tree. Choices: a. Keys. b. Sapling.

b