during and in the aftermath of the financial crisis of​ 2007-2009, planned investment fell​ substantially, despite significant decreases in the real interest rate. which of the following factors related to the planned spending function could explain​ this? ​ (check all that​ apply.) a. an increase in financial frictions. b. a decrease in the marginal propensity to consume. c. a decrease in autonomous net exports. d. a decrease in​ firms' planned autonomous investment.