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: Having to work late. Sentence 1: Fred had to finish up a project for work. Sentence 2: He wanted to finish so he could get home. Sentence 3: But his boss was making him stay. Sentence 4: Fred couldn't believe it. Choices: a. His boss did not let him home until ten. b. She scored a grand slam at their inaugural game.
a