In the former USSR, state planners decided what was to be produced. They passed orders down to factories, allocating raw materials, workers, and other factors of production to them. This is an example of (a) :

Command Economy

Explanation:

Command economy is an economic system in which the economic resources is left in the hands of the government, in this system, the economic problems of what to produce, how to produce, for whom to produce and when to produce are solved by the government through a central planning committee.

The operators of this system believe the market will not be efficient enough in the allocation of resources because of market failure