Given the task definition and input, reply with output. 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'.

Sentence 1: Our treehouse was on the ground. Sentence 2: We were afraid of heights so we found a tree with a big hole. Sentence 3: We climbed inside and sat there to talk for hours. Sentence 4: We played with the little bugs in the dirt. Sentence 5: We met there every day for years. Choices: a. Treehouse. b. New Chickens.
a