Which of the following can we be sure is true?YOUR ANSWERYour AnswerA lower retirement age must decrease the supply of labour.As wages increase the quantity supplied of labour will increase.A change in the school leaving age will impact on the supply of labour.The supply of labour is finite.

The statement we can be sure is true is: "A change in the school leaving age will impact on the supply of labour."

Here's why:

1. "A lower retirement age must decrease the supply of labour." - This is not necessarily true. While a lower retirement age might mean that some people leave the workforce, others might choose to continue working. Therefore, the supply of labour might not decrease.

2. "As wages increase the quantity supplied of labour will increase." - This is also not necessarily true. Higher wages could lead to an increase in the supply of labour, as more people are incentivized to work. However, it could also lead to a decrease in the supply of labour, as people who are already working might choose to work fewer hours if they can maintain the same standard of living with higher wages.

3. "A change in the school leaving age will impact on the supply of labour." - This is likely to be true. If the school leaving age is increased, fewer young people will be available to work, which would decrease the supply of labour. Conversely, if the school leaving age is decreased, more young people would be available to work, which could increase the supply of labour.

4. "The supply of labour is finite." - This is not necessarily true. The supply of labour can change based on a variety of factors, including changes in population, immigration, education, and technology. Therefore, it is not finite.