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: Don was 62 and noticed a blurriness in his vision. Sentence 2: He was diagnosed with cataracts, which are flaws in the lens. Sentence 3: He learned that there are artificial lens with varying focal lengths. Sentence 4: He had surgery replacing the lens in each eye. Sentence 5: He threw away his glasses and now has 20-20 vision. Choices: a. Nightmares. b. Cataracts.

b