In a multiple regression analysis with a continuous responde y, and 2 explanatory variable x7 and x2, the coefficient of x7 is estimated as 3.3. Which of the following is false? Select one: a. The slope of a scatterplot of yvs x7 is 3.3 b. A unit increase in x/ produces an incerase of 3.3 in the mean response, provided that x2 is held constant. c. If x7 and *2 are uncorrelated, adding *2 to the regression does not change the estimated coefficient of X1. d. The variance of the estimated coefficient of x] is a minimum if x7 and *2 are uncorrelated