Why Could a Labour Supply Curve Be Backward Bending

Multiple Choice

Why could a labour supply curve be backward bending

A) As wage increases, the opportunity cost of leisure increases even more.
B) As wage increases, a person can enjoy more leisure because of the income effect
C) As wage increases, the substitution effect dominates, then the income effect dominates.
D) As wage increases, the income effect dominates, then the substitution effect dominates.