Which of the Following Formulas Is Used to Calculate the Inflation

Which of the following formulas is used to calculate the inflation rate?

A) inflation rate = 100 × $\left( \frac { \text { CPI in current year } } { \text { CPI in baseperiod } } \right)$
B) inflation rate = 100 × $\left( \frac { \text { CPI in prev ious year } } { \text { CPI in current year } } \right)$
C) Inflation rate = 100 × $\left( \frac { \text { CPI in current year - CPI in prev ious year } } { \text { CPI in previous year } } \right)$
D) Inflation rate = 100 × $\left( \frac { \text { CPI in previous year - CPI in current year } } { \text { CPI in current year } } \right)$
E) inflation rate = 100 × $\left( \frac { \text { CPI in base year } } { \text { CPI in current year } } \right)$