The correct options are
A The redistribution of land by the Bolsheviks
B The ideological clash between the Bolshevik and non-Bolshevik principles of socialism
D The fear of the spread of communism, harboured by western European countries
The redistribution of land by the Bolsheviks created massive turmoil across Russia. The supporters of private property took harsh steps against the peasants who had seized land. Meanwhile, western European countries were afraid of the developing socialist tendencies in Russia. They feared this could cause turmoil on their own soil. So, the non-socialist Bolsheviks were indirectly backed by the French, American, German, British, and Japanese troops.
These different factions thus competed to control Russia's future, leading to a full-fledged multi-party Civil War.