What is one of the primary reasons for the collapse of socialist/communist economic systems, particularly in the soviet union?

Of the following given choices;

a.government failure to distribute resources effectively.

b. the inability of the people to work as a group.

c.lack of government oversight.

d.profits got too high?

The answer is; A

Most of the benefits of the industrial outputs were being directed to the military (with percentages estimated to an astounding 70%) hence leaving meager resources for the rest of the civilian population. This dis-incentivized the workers, resulted in an uprising, hence  causing an economic collapse of the soviet union socialist system.