The correct answer is "D)".
Inflation is the sustained increase in the price of goods and services in a given economy. This means that if goods suffer from inflation in a given period, you will be able to buy less for the same money in the lapse of that period.
Your money is in the bank and grows 5% over a year. However, the price for goods and services (inflation) grows 7% during that same period. As a consequence, regardless of the growth of your savings (nominal return), you will have a reduction in your purchasing power of 2% (real return).