Answer:
B. Less than $1/unit
Explanation:
Base on the scenario been described in the question, the long run average total cost will be less than one dollars, because as it doubt is production using all inpute the average total cost is decreasing , that's why it reduced from $1 to less than $1 .
economies of scale are the cost advantages that enterprises get due to their scale of operation normally calculated by the amount of output produced, with cost per unit of output decreasing with increasing scale