Option 1 -> Flexible - Incorrect. In the short run, not all factors are flexible; some are fixed.
Option 2 -> Remain Constant - Correct. By definition, in the short run, at least one factor of production (typically capital like machinery, buildings) remains fixed or constant.
Option 3 -> Increases - Incorrect. Factors of production don't necessarily increase in the short run; some remain fixed.
Option 4 -> Decreases - Incorrect. Factors of production don't necessarily decrease in the short run; some remain fixed.
Hence, Option 2: Remain Constant -> The short run in economics is defined as a period during which at least one factor of production cannot be changed and remains fixed. Typically, capital (buildings, machinery, equipment) is considered the fixed factor, while labor can be varied. This distinguishes the short run from the long run, where all factors of production are variable and can be adjusted. -> correct