GDP deflator is :

$\frac{\text{Nominal GDP}}{\text{Real GDP}}+100$ $\frac{\text{Real GDP}}{\text{Nominal GDP}}+100$ $\frac{\text{Nominal GDP}}{\text{Real GDP}}×100$ $\frac{\text{Real GDP}}{\text{Nominal GDP}}×100$

$\frac{\text{Nominal GDP}}{\text{Real GDP}}×100$

The correct answer is option (3) : $\frac{\text{Nominal GDP}}{\text{Real GDP}}×100$ The GDP deflator is the ratio of nominal GDP to real GDP multiplied by 100 to express the result as an index .