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: Carol went as usual to practice at the indoor gymnasium. Sentence 2: She saw a new girl practicing under the guidance of her trainer. Sentence 3: She felt irritated, because she wasn't informed about her. Sentence 4: The trainer came to her and introduced her to the girl. Sentence 5: She couldn't believe that the girl was her childhood friend. Choices: a. Casino. b. Gymnast girl.

b