When did the caste system evolve into a four tiered hierarchy?A.) when the Aryans ruled over the region - They arrived in 1500BC and developed the grouping of people based on their status and activities in life.
i'd say B would make the most sense
C. Soviet Union begins a war with Afghanistan (<span>The </span>Soviet–Afghan War<span> lasted over nine years, from December 1979 to February 1989).
</span><span>A. Reforms such as glasnost and perestroika instituted in Soviet Union.
</span>E. Mikhail Gorbachev becomes the leader of the Soviet Union (He was the country's head of state from 1988 until 1991).
D. Soviet government attempts to overthrow Mikhail Gorbachev (1991 August Coup was an attempt by members of the Soviet Union's government to take control of the country from Soviet President and General Secretary Mikhail Gorbachev).
<span>B. Boris Yeltsin becomes president of the established Russian Federation
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There are many steps that people took to end the racial caste system in the United States, but I think putting blacks into the schools was definitely a step in the right direction. ( I don't know if this what you wanted) Also, In India, there actually was a stronger caste system than in the United States but thanks to Muhammad Gandhi it now doesn't exist. He would dress up in the lower classes clothes and live in their villages which forced people to look at the lower class and to see what was going on around them.