The Figure Below Shows the Supply Curve for Labor

The figure below shows the supply curve for labor.Figure 16.1

-Why is the market supply curve of labor positively sloped though individual supply curves are backward-bending beyond a certain wage rate?

A) People tend to work less when wage rate increases.
B) Every individual laborer has equal trade offs between labor and leisure.
C) People tend to substitute labor for leisure.
D) People work more for the fear of losing their jobs and becoming unemployed.
E) All the individual supply curves do not bend backward at one particular wage rate.