Why did the theory of communism fall when put into practice

Stalin for example put communism into play. With collectivism everyone worked for the state and had to meet quotas. The farmers and people were unable to meet these impossible quotas so they lied and said the quotas were met. This led to Russia selling all the resources and not keeping any because no one mer quotas to be able to feed themselves and sell to countries. This created a huge poverty and millions of people died. So one aspect of communism that failed was that it created poverty. That's all I can think of. Hope this helped.

The answer is d. spain.