Answer:
The correct answer is - a shift from individual to collect farms
Even though it may seem that the collectives are advantageous in the agriculture, we have to take into consideration that is was a socialist system, so the collectives were operating in different manner. When people had their own farms, they were producing enough food for themselves, and maybe something for sale/trade, but in accordance to their needs and circumstances, but when the collective farms were introduced, it all changed. The people were no more able to produce what they want and need, but the government officials were doing that, by creating annual planing about what should be farmed, in which way, and in what amount, and that caused huge problems with lack of food, because the agriculture is very unpredictable, and on top of that, it is practically impossible to create an accurate plan for hundreds of million of people.