help me choose the correct answers, thanks much.

Question 15 4 pts Once a firm enters the long run, the firm no longer has fixed inputs incurring fixed costs. O True O False Question 13 4 pts The period of time long enough to allow a firm to vary all of its inputs, to adopt new technology, and to increase or decrease the size of its physical plant is considered the O immediate run. QO short run. O long run. O short range. (O cannot be determined with the given information. Question 12 4 pts If Economic profit equals zero, then the firm should shut down in the short run and go out of business in the long run. QO True O False Question 11 4 pts Economic profit equals total revenue minus total costs including explicit fixed costs, explicit variable costs, implicit fixed costs, and implicit variable costs. O True QO False