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 does not connect with the rest of the story, indicating your choice as 'a' or 'b'. If both sentences are plausible, pick the one that makes less sense.

Title: Katie Courier. Sentence 1: Katie was asked by a stranger to deliver a package. Sentence 2: She unwisely took the package of unknown contents. Sentence 3: While delivering the package it tore open. Sentence 4: Some of the toxic substance in it leaked out. Choices: a. Tim had less tickets than any of his friends. b. She became very ill at the exposure to the contents.
a