Russia's leader, czar alexander ll, tried to modernize russian society in the late 19th century. one of his major accomplishments was ending serfdom, a forced-labor system similar to slavery. however, alexander ii was assassinated in 1881, and the czars that followed him reversed many of his reforms. these leaders were so harsh that a group of revolutionaries called the bolsheviks eventually rebelled against them and overthrew the russian government in 1917. which statement best describes the main idea of the passage? o a. efforts to modernize russia in the 19th century failed to protect the country from a revolution. o b. russian leaders were called czars until the russian government was overthrown in 1917. o c. czar alexander ii was responsible for the rise of the bolshevik rebel group in russia. o d. the system of russian serfdom was a forced-labor structure that was similar to slavery.