Choose the incorrect option from the following with reference to production in the short run.

The firm can change more than one factor in short run.

The correct answer is Option (2) → The firm can change more than one factor in short run.

In the short run, only one factor of production (usually labour) is variable, while other factors like capital or land remain fixed. Therefore, the firm cannot change more than one factor in the short run.

The law of variable proportions is applicable. Correct (as a statement about the short run). The Law of Variable Proportions (or Returns to a Factor) specifically explains how output changes when one factor is varied while others are fixed, which is the defining condition of the short run.

The firm experiences returns to a factor → Correct (as a statement about the short run). The term "returns to a factor" is the concept used to describe the change in output when one factor (the variable factor) is increased while others are fixed. This is the phenomenon studied in the short run.

The law of diminishing marginal returns is applicable → Correct (as a statement about the short run). The Law of Diminishing Marginal Returns is a stage within the Law of Variable Proportions and is the central limiting principle in short-run production. It states that adding more units of a variable factor to a fixed factor will eventually lead to smaller increases in total output.