Concept:Supply of labour is the number of people who are willing and able to work at a particular wage rate.
Explanation:The supply of labour shows how many workers offer themselves for employment at different wage levels.
At any given wage rate, only those who are willing and prepared to accept that wage are counted.
The phrase “at a given wage rate” points to the quantity of labour supplied, not the entire labour force.
The labour force refers to all persons of working age who are employed or unemployed, regardless of a specific wage rate.
Demand for labour, on the other hand, comes from employers who want to hire workers.
Therefore, the correct meaning is the supply of labour.
Answer:B. supply of labour.