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: Mark had always wanted to be an astronaut. Sentence 2: His mom and dad told him to be realistic, but he never wavered. Sentence 3: As an adult, he majored in astrophysics and became a teacher. Sentence 4: Mark's parents were pleased with his more-reasonable line of work. Sentence 5: And Mark himself was thrilled to talk about space- all day, every day! Choices: a. Astronaut. b. Finally.

a