yingjaiv0v

Since all quantity of factor of production can be doubled,
the production is in long run.
Given that the firm's profit has not been doubled even holding the price of its output constant,
the average cost of production must be increased as a result of diseconomies of scale.
The firm is producing at an output level above the efficient level,
and thus faces an increased average cost.

(Based on my F4 knowledge, 求指正and真心求教if answer in this way works)