Output Average Total Cost $10 3 4 2 5 4 8 What is this firm's efficient scale? Oa. 1 unit of output Ob. 3 units of output Oc. 4 units of output Od. 6 units of output Skip Submit AnswerPlease submit the answer and then watch the video feedback. At what quantity of output will the marginal-cost curve cross the average-total-cost curve? Oa. 3 units of output Ob. 4 units of output Oc. 5 units of output Od. The two curves will not cross