The two options that support the claim that this passage is an allegory for the Great Purge are:
B. The false confessions extracts from the four pigs
D. The slaughter of the pigs by the dogs at napoleons order
The Great Purge was a period of terror that extended from 1936 to 1938 in the Soviet Union. During those years, hundreds of people were killed as the government tried to repress leaders of the political party and the army as well as landlords. Killing people after having them confess to false accusations is a common practice in authoritarian governments. It is a way to instigate fear and force people into being loyal.
Animal Farm is known for being an allegorical portrait of Stalinist Russia. Its author, George Orwell, was a democratic socialist.