Answer:

In the short run, only variable factors can be easily changed. Fixed factors, on the other hand, cannot be easily changed or adjusted in the short run.

Explanation:

1. Variable Factors:
Variable factors are inputs that can be easily changed or adjusted in the short run. These factors include labor, raw materials, energy, and other inputs that can be increased or decreased based on the level of production. For example, a manufacturing company can easily hire more workers or purchase additional raw materials to increase production in the short run. Similarly, they can reduce the number of workers or limit the purchase of raw materials to reduce production.

2. Fixed Factors:
Fixed factors, on the other hand, cannot be easily changed or adjusted in the short run. These factors include capital equipment, land, buildings, and other inputs that require a longer time period to adjust. For example, it is not feasible for a company to quickly expand its factory size or purchase new machinery in the short run to increase production. These factors require a significant investment and planning, and therefore cannot be easily changed in the short run.

3. All the Factors:
While all factors of production can be changed in the long run, in the short run, only variable factors can be easily adjusted. This is because variable factors do not require significant investment or planning, and can be increased or decreased relatively quickly based on the immediate production needs.

Conclusion:
In summary, in the short run, only variable factors can be easily changed or adjusted. Fixed factors, such as capital equipment and land, require a longer time period and significant investment to adjust. Therefore, option 'A' - variable factors, is the correct answer.