Altering photographs was part of Joseph Stalin's effort to

purge those who threatened him.

censor the Communist Party.

persecute visual artists.

change historical facts.

The correct answer is change historical facts

Many people who used to work with him eventually became state enemies according to him. He would delete all records of their existence and remove them from photos to make it seem as if they never worked together and as if he was the one that came up with everything.