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: Rina grew up with a friend named Duvonna. Sentence 2: Rina loved her friend and they were close. Sentence 3: She started to realize they weren't good friends. Sentence 4: They started to grow apart. Sentence 5: Rina was okay with that. Choices: a. Changing Phone Plan. b. Old friends.
b