Q: 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: Tires. Sentence 1: The man checked the tires. Sentence 2: He recommended replacements. Sentence 3: The customer agreed without checking cost. Sentence 4: The man installed replacements. Choices: a. The customer was shocked by the high price. b. Within a month Ken was a comfortable swimmer.
A:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
a