Let the sum of money be \(P\) and the rate of interest be r.
According to the formula,
Amount \((A)\) = \((P)\) Principal \(\times\)\([1-\frac{r}{100}]^n\)
\(A=8P=P\times[1+\frac{r}{100}]^3\)
After solving the equation, we get \(r=100\)
\(A=16P=P\times[1+\frac{100}{100}]^t\)
After solving the above equation, we get \(t=4\) years.
The correct option is (B)