Option : (A)
Here,
Sum of first 3n terms=sum of next n terms
i.e. S3n = S4n - S3n
i.e. 2S3n = S4n
Sum of 2n terms is S2nand sum of next 2n terms is given by S4n-S2n
Now,
\(\frac{S_{4n}-S_{2n}}{s_{2n}}\) = \(\frac{S_{4n}}{S_{2n}}\)
So, ratio of the sum of first 2n terms to the next 2n terms is 1:5