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: Regina had forgotten to call her best friend. Sentence 2: It was her friend's birthday. Sentence 3: She tried to call her friend no one answered. Sentence 4: Regina decided to stop by her friend's house. Sentence 5: She was surprised to discover her best friend was out of town. Choices: a. First Driver to the Finish Line. b. Missing Birthday Girl.
b