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: Stinging Tornado. Sentence 1: Carol went shopping in town and parked in the town center. Sentence 2: When she finished shopping, Carol returned to her car and headed home. Sentence 3: She didn't realize it but a swarm of 20,000 bees followed her. Sentence 4: Passerby's alerted the police and experts were called in. Choices: a. Beekeepers said the bees were trying to rescue their queen. b. We could not solve the puzzle.
a