Detailed Instructions: 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.
Q: Title: The Notebook. Sentence 1: Dan was studying chemistry in college. Sentence 2: One day he couldn't find his chemistry notebook. Sentence 3: He searched frantically, but could not find it anywhere. Sentence 4: After two weeks, his roommate returned Dan's notebook. Choices: a. He had accidentally picked it up and put it in his own backpack. b. She asked the theater manager for a refund, and was given one.
A:
a