Final answer:
An increase in the real interest rate is likely to decrease consumption, and its effect on real GDP can vary depending on other factors. None of the given options are correct.
Step-by-step explanation:
With an increase in the real interest rate, consumption is likely to decrease. This is because higher interest rates make borrowing more expensive, which reduces consumer spending. On the other hand, an increase in the real interest rate is likely to have a mixed effect on real gross domestic product (GDP). It may decrease real GDP if the decrease in consumption outweighs any increase in investment spending. However, it could also increase real GDP if the decrease in consumption is offset by an increase in exports or other components of aggregate demand.