The denominator of the seventh term is
125
216
343
512

Answer: Thus, Third option is correct.
Step-by-step explanation:
Since we have given that
[tex]1,\dfrac{1}{8},\dfrac{1}{27},\dfrac{1}{64},...............\dfrac{1}{n^3}[/tex]
So, we can see the pattern:
General term of the series is given as
[tex]\dfrac{1}{n^3}[/tex]
So, we just put the value of n = 7, to get the required denominator:
[tex]\dfrac{1}{7^3}=\dfrac{1}{343}[/tex]
Hence, the denominator of the seventh term is 343.
Thus, Third option is correct.