The correct answer to this open question is the following.
Although there are no options attached, we can say the following.
The challenges that most contributed to unrest in Russia in the early 1900s were famine, poverty, class struggles, and wars.
Those were the times of Russian Tsar Nicholas II, who ruled a nation with a minority very rich, and most of the population under poverty and famine. Russian people suffered from bad living conditions, bad working conditions, the abuse of power by the elite, and very high taxes. These factors made people protest and organize strikes in the factories.