Answer: The answer is (d) Compounding.
Step-by-step explanation: We are given four options out of we are to select the best way through which we can achieve significant increases in interest after all in a savings account.
Increases in principle and increases in time will not give the result, because we are talking about a fixed amount of money for a fixed time.
Also, increases in interest is not in our hand.
So, only we can do is compounding. Here, in same amount of money and time, the rate of interest will automatically increase.
Thus, the correct option is (d) Compounding.