Answer: C 2.5%
Step-by-step explanation:
The "Rule of 72" is a easy way to calculate how much time an investment will take to double with a given fixed annual rate of interest.
Just we have to divide 72 by the annual rate of return(r), we can get a rough estimate of how many years it will take to double the initial investment .
Now, in given problem: Let 'r' be the rate of interest
Time to double the amount=29 years
Thus by rule 72 ,
Therefore, C is the right option.