For all $n \in N, \frac{3^n-1}{2} \geq$

• A

  $n^2\left(2^{n / 2}\right)$
• B

  $n^2\left(3^{\frac{n-1}{2}}\right)$
• C

  $n^3\left(3^{\frac{n-1}{2}}\right)$
• Correct answer
  D

  $n\left(3^{\frac{n-1}{2}}\right)$

Hence, the correct answer is option: 'D'.