Pareto optimality is the condition in which

A) the distribution of income is equal.
B) no change is possible that will make some members of society better off without making at least one other member of society worse off.
C) firms are forced to internalize the effects of all externalities.
D) it is possible to make one person better off without making someone else worse off.

Pareto optimality, or Pareto efficiency, is a state of allocation of resources in which it is impossible to make any one individual better off without making at least one individual worse off. This concept does not necessarily imply an equitable distribution of resources, but rather that no further improvements in individual welfare can be achieved without harming someone else.