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: Derby. Sentence 1: The first of May every year is the running of the Kentucky Derby. Sentence 2: David was a farmer in Kentucky. Sentence 3: One of his mules went into labor. Sentence 4: The baby mule was born on Derby day. Choices: a. So he decided to stop using it. b. So David named the new mule Derby!
a