Which of the following is true of an individual’s labor supply curve?

a. When higher wages are offered, the cost of forgoing labor time to gain greater leisure time increases; thus, workers tend to substitute labor for leisure—the substitution effect.

b. At higher wage levels, the income from a given quantity of labor increases, and a worker may feel that he or she can afford more leisure—the income effect.

c. If the substitution effect is stronger than the income effect, the individual’s labor supply curve is upward sloping.

d. If the income effect is stronger than the substitution effect, the individual’s labor supply curve is backward bending.

e. All of the above are true.