Given the following regression equation: E(DV) = 35 + 9(X(1) + 2(X(2) The coefficient for X1 would indicate that: O a. Two observations that differ by one point on X1 would differ by 9 points on the DV, assuming the two observations did not differ on X2 O b. X1 is a statistically significant predictor O c. X1 increases as X2 increases O d. X1 causes a 9-unit change in the DV O e. X1 has a stronger effect than X2