The answer is indeed letter D. He wanted to expose violent tactics used by oppressive governments.
Explanation:
"Animal Farm" is an allegorical novella by George Orwell in which the results of the Russian Revolution are criticized. The animals represent the Russian people who fought believing they would achieve an equal society, only to be disappointed by their leaders in a very violent manner. The Great Purge exemplifies that fact. It happened between 1936 and 1938, when over 600,000 people were killed. The accusations were random and false, the intention of the Stalinist government being the destruction of their potential enemies and the control over the population. In the novella, after the animals expel their human owner and take power, the same practices take place. The pigs, being the smartest animals, become the leaders. They realize that being is power brings them comforts and advantages. Not wishing the other animals to claim the same treatment for themselves, the pigs begin to spread false propaganda. They kill any animal that poses a threat to their political advantage after accusing them of treason. Orwell is, thus, exposing the violent tactics of the Russian government by means of his characters.
