No idea for explain

Which of the following is a correct difference between short run and long run, in terms of production time frame? Short run is any length up to 3 months; long run is any length longer than 3 months. Short run is the very short period when no costs are incurred; long run is anything longer than that. Short run is the period when profit is negative at the beginning of a new business; long run is when profit turns positive later. Short run is the period of time when some input is fixed; long run is when all inputs are variable