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 Zen Garden. Sentence 1: Riley liked Japanese culture. Sentence 2: He had a Zen garden in his office. Sentence 3: It relaxed him to play around with it. Sentence 4: His coworkers had lots of questions about it. Choices: a. Riley was happy to teach them about Japan. b. She had to throw out and replace the tainted food.
a