ભૂમિતિ શ્રેણી $\sqrt{7}, \sqrt{21}, 3 \sqrt{7}, \ldots$ માં $n$ પદોનો સરવાળો શોધો.

• A
  $\frac{\sqrt{7}(\sqrt{3}+1)}{2}\left[(3)^{\frac{n}{2}}-1\right]$
• B
  $\frac{\sqrt{7}(\sqrt{3}-1)}{2}\left[(3)^{\frac{n}{2}}-1\right]$
• C
  $\frac{\sqrt{7}(\sqrt{3}+1)}{2}\left[1-(3)^{\frac{n}{2}}\right]$
• D
  $\frac{\sqrt{7}(\sqrt{3}-1)}{2}\left[1-(3)^{\frac{n}{2}}\right]$