Answer to Question 1
Famine (holodomor), induced by Soviet leaders to blunt independence hopes, killed millions of ethnic Ukrainians. Soviet leadersmost notoriously, Josef Stalindisregarded these costs, and by 1940, virtually all of the Soviet Union's farmed land was collectivized, against the will of the farmers.
Ukraine figured especially strongly during these events; it was known as breadbasket of the Soviet Union, mainly for its wheat. Stalin's apparatus sifted Ukrainian wheat out of Ukraine, distributing it in the vast USSR hinterland, dumping it at low prices abroad and using that income to fund industrialization. That historical legacy too feeds into modern anti-Russian sentiment among ethnic Ukrainians.
Answer to Question 2
D