Answer:
A. double
Explanation:
Rule 70 is used to calculate the numbers of years it takes for an investment or variable to double in value given a certain growth rate. In this case, the variable is prices and the growth rate is inflation rate. It is calculated by dividing number 70 by inflation rate.
For example;
Assume inflation rate is 6%, the prices will double in ; 70/6 = 11.7 years
And if inflation is 2%, the prices will double in 70/2 = 35 years