Answer: Option D
Explanation: In simple words, short run refers to the time frame in which all the factors of production are fixed while in the long run all of them are variable.
This happens due to the fact that in the short run if the company goes for changing the level of inputs than the opportunity that were availing in that time period will be gone by then leading to losses as the total time frame is very less in short run.
On the other hand, firms tends to have greater life in the market and keeps developing themselves with the changing forces of market.