Which of the Assumptions Listed Below Are Necessary in Order

Multiple Choice

Which of the assumptions listed below are necessary in order for the coefficients in a partial regression equation to be interpreted as the average change in the criterion variable associated with a unit change in the appropriate predictor variable holding other predictor variables constant?

A) The predictor variables must be correlated.
B) The variance among predictor variables must be equal.
C) The criterion variable must be normally distributed.
D) The predictor variables must be uncorrelated.
E) None of these are necessary assumptions.