It might be said that Sergei´s reaction towards Yoni at his door might be option D. he might have been frightened because Yoni could discover the gold fish. so his reaction was kind of harsh, he did not what to answer the questions and he wanted the boy to go away from his house.
I think i remember the answer...it was C....
The answer you put is the right one.
Publishing Gulliver's Travels had the goal of exposing corrupt Whig politics to the society and mocking them pointing out to all their flaws and crookedness. In addition, he wanted to present the pettiness of mankind and how it can lead to the downfall of society and civilization.