An economy is efficient when: the problem of scarcity is eliminated. all opportunities to make some people better off without making other people worse off have been taken. all opportunities to make some people worse off without making other people better off have been taken. output is distributed equitably.

all opportunities to make some people better off without making other people worse off have been taken

Explanation:

Economic efficiency means an economic condition where every asset is efficiently distributed to benefit each person or organization in the best possible way whilst reducing wasteful spending. If the system is economically sound, any modifications to assist one individual will affect another.