For the following labor supply curve QL^s= -200+200W-50R, where QL^S= quantity of labor supplied, W=wage rate, and R= average rainfall per month, the change in labor supplied as rainfall increases constitutes a change base on

a) A movement along the supply curve

b) a shift in the supply curve

c) either a shift or a movement along the supply curve

D) Neither a shift nor a movement along the supply curve

E) None of the above