What Does Productive Efficiency Mean

What does productive efficiency mean?

A) A product is being produced at the lowest possible short-run average cost but not necessarily at the lowest long-run average costs.
B) A product is being produced at the lowest possible long-run average cost but not necessarily at the lowest short-run average costs.
C) A product is being produced at the lowest possible short- and long-run average costs.
D) A product is being produced at the lowest possible marginal costs.