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: The Mailman. Sentence 1: Kelley has worked for the post office for six years. Sentence 2: He normally works at the counter, but occasionally has to carry mail. Sentence 3: The last time he delivered mail, he decided not to deliver it all. Sentence 4: He threw away many people's mail and slept in his truck. Choices: a. Kelley's boss quickly found out and he was fired promptly. b. He simply moved out while she was at work and never told her.
a