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: Bob was trying to take apart his bookcase. Sentence 2: When he'd put it together he'd used nails on the back. Sentence 3: Bob was having a difficult time pulling the nails out. Sentence 4: He hit on the idea of using a very small flat blade screwdriver. Sentence 5: Bob was able to pull all the nails and take apart the bookcase. Choices: a. Christmas Tree. b. Shelved.
b