You will be given a definition of a task first, then some input of the task.
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: Bubble Bubble. Sentence 1: Cora wanted to blow a bubble with her gum. Sentence 2: She chewed and blew. Sentence 3: Her brother came and explained how to do it. Sentence 4: Cora tried one more time. Choices: a. She blew a huge gum bubble. b. She threw it out and decided to buy a new one.
Output:
a