Final answer:
The labor supply curve shifts when workers change the number of hours they want to work at a given wage, affected by factors other than the wage rate itself. Therefore correct option is A
Step-by-step explanation:
The labor supply curve shifts when workers change the number of hours they want to work at any given wage. This is indicated by the option (a). Several factors can cause this shift, such as changes in workers' preferences, government policy, and training in the field. Changes in the wage rate cause a movement along the labor supply curve rather than a shift. A shift in the supply curve involves factors other than the wage rate.
Factors that can shift the labor demand curve include changes in the quantity demanded of the product that labor produces, changes in labor productivity, technology, and factors affecting the number of companies or the price and availability of other inputs. When employers develop new technology, this can increase productivity, which may shift the labor demand curve, not the supply curve, and is related to option (d). On the other hand, needing to hire more people, mentioned in option (e), could be a result of a shift in the labor demand curve, not the cause of the shift in labor supply.