6. The substitution effect of an increase in the interest rate earned bysavers leads to

       a.  an increase in savings due to thesubstitution effect;

       b.  a decrease in savings due to the substitutioneffect;

       c.  an increase in savings due to the incomeeffect;

       d.  a decrease in savings due to the incomeeffect;

       e.  a. and d.*

为什么选E