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: Bravery. Sentence 1: Sam was very brave. Sentence 2: Sam knew there was nothing that could scare him. Sentence 3: One day he was at a bank when robbers with guns came in. Sentence 4: The robbers asked if anyone wanted to be a hero. Choices: a. At last, the crunch of apple as Ricky brought out his prize. b. Sam stood up and was immediately shot.
a