A bank develops the following linear discriminant model of the credit quality (i.e., a higher Z means a better credit quality) based on their own loan database: Z = B1X1 + B2X2 + B3X3 where X1 is debt to asset ratio (long-term debts/total assets), X2 is return on asset (net income/total assets), and X3 is earnings retention ratio (retained earnings/total assets). Which statement below about the coefficients of three variables is correct? Select one: a. B1 is positive; B2 is negative; 83 is positive b. B1 is negative; B2 is positive; B3 is positive c. B1 is positive; B2 is positive; B3 is negative d. B1 is positive; B2 is positive; B3 is positive e. B1 is negative; B2 is negative; B3 is negative