6. In a regression model with p - 1 predictor variables chosen from a set of P - 1 possible predictor variables, which of the following indicates that bias is not a problem with the model?
a. Mallow's Cp < p (small p)
b. Mallow's Cp ≤ P(cap P)
c. Mallow's Cp > p (small p)
d. Mallow's Cp > P (cap P)
