If NGDP Is Nominal GDP and RGDP Is Real GDP,which $\times$

If NGDP is nominal GDP and RGDP is real GDP,which of the following can be used to calculate inflation?

A) percent change in NGDP + percent change in RGDP
B) percent change in NGDP - percent change in RGDP
C) percent change in NGDP $\times$ percent change in RGDP
D) percent change in RGDP + percent change in NGDP
E) percent change in RGDP - percent change in NGDP