Why Does Division of Labour Increase Productivity

Why does division of labour increase productivity?  

A)  because tasks can be assigned according to individual tastes and abilities 
B)  because each worker must learn each of the numerous tasks in the total production process 
C)  because specialization of labour allows for the introduction of cheaper, less-sophisticated production techniques 
D)  because managers can force workers to produce goods that are valued more highly than the costs of producing them