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: My son's sister was born prematurely. Sentence 2: She had a heart defect. Sentence 3: It was corrected shortly after birth by surgery. Sentence 4: He was very worried about her. Sentence 5: Ever since, he has been extremely protective over her. Choices: a. Sister. b. The Agent.

a