Given the task definition and input, reply with output. In this task, you're given the title of a five-sentence story, the first four sentences, and two options for the fifth sentence as a and b. Your job is to pick the sentence option that seamlessly connects with the rest of the story, indicating your choice as 'a' or 'b'. If both sentences are plausible, pick the one that makes more sense.

Title: Brushing Away. Sentence 1: Heather never brushed her teeth. Sentence 2: One day, her tooth started hurting. Sentence 3: Her parents took her to the dentist and they gave X-rays. Sentence 4: The dentist found out Heather had two cavities. Choices: a. He filled them right away. b. I decided I would be better off as a scorekeeper.
a