Exhibit 18-10 Consumption function A graph shows the consumption function. Real disposable income in dollars is on the horizontal axis. Real consumption in dollars is on the vertical axis. An upward sloping curve is labeled C_1. An upward sloping curve labeled C_2 is parallel and below C_1. In Exhibit 18-10, which of the following could cause the shift from C1 to C2? Group of answer choices higher interest rates lower tax rates an increase in disposable income a decrease in disposable income