A Basic Distinction Between the Long Run and the Short

A basic distinction between the long run and the short run is that

A) if a firm produces no output in the long run, it still incurs a cost.
B) the opportunity costs of production are lower in the short run than in the long run.
C) in the long run, some inputs are fixed, while in the short run, all inputs are variable.
D) in the short run, complete adjustment of all inputs is impossible, while in the long run all inputs can be adjusted.