hello! econ mcq how do i complete this?

Scrooge McDuck charges Donald Duck a nominal interest rate of 20% on any one-year loan Donald Duck wishes to make. To understand how much richer he will be from each loan Scrooge McDuck hires advisors to collect information about the economy. The information collected is shown in the table below. Real GDP growth rate 5% Increase in GDP deflator 10% Given this information what is the real interest rate Scrooge McDuck earns on one-year loans to Donald Duck? Select one: O a. 20% o b. 10% O c. 15% O d. 5%