​Select the fraction from among the given options that can replace the question mark (?) in the following series.​

​$$\frac{1}{25},\frac{1}{49},\frac{1}{81},$$ ?​

Given: ​$$\frac{1}{25},\frac{1}{49},\frac{1}{81},$$ ?​^​

Logic: The square of denominator are starting from 5, 7, 9.

Now, the next denominator will be: 

9 + 2 = 11

11² = 121

now, the final term will be: $$\frac{1}{121}$$​

Thus, the correct Option is (a): $$\frac{1}{121}$$

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