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: Lost Wallet. Sentence 1: Tom lost his wallet downtown. Sentence 2: He looked everywhere for it. Sentence 3: After a week he got it back in the mail. Sentence 4: Everything was still in it. Choices: a. She covered it with a towel, hoping nobody would notice. b. Tom never found out who returned it.
b