What is the rate of the compound interest?
A. A certain amount invested at the compound interest rate amounts to Rs. 1331.
B. The amount was invested for a period of three years.

In the context of Compound interest, we have to have principal, Amount, rate of interest and the duration. We can find the interest charged by subtracting the principal from the amount. 

In this first statement, we are only given the amount. Since, we don't have principal and the duration, we can't find the rate of interest with this statement alone. 

In the second statement, we are given only the duration. Since we don't have principal and the amount, we can't find the rate of interest with this statement alone. 

Now, even if we combine both the statements, we will have the amount and the duration. But again, we don't know the principal. Hence, we can't find the rate of interest even using both the statements.