Perfectly Competitive Markets Achieve Efficiency in the Allocation of Resources

Perfectly competitive markets achieve efficiency in the allocation of resources by producing:

A) all of the units that are worth less than the cost of producing them and none of the goods that cost more than they're worth.
B) all of the units that are worth more than the cost of producing them and only goods whose price is less than their average variable cost.
C) none of the goods that people value highly and only goods that people don't value.
D) all of the units that are worth more than the cost of producing them and none of the units that cost more than they're worth.