29. Suppose you are trying to use linear regression analysis to determine whether the effect of one variable, X1, on another variable, Y, depends upon the value taken by a third variable, X2. Which regression model should you run.

A. Yi = 0 + 1X1i + 2X2i + ei

B. Yi = 0 + 1X1i + 2X2i + 2X1iX2i + ei

C. X1i = 0 + 1Yi + 2X2i + ei

D. X1iX2i = 0 + 1X1i + 2X2i + 2Yi + ei

E. None of the above