Let $n$ be a positive integer. If the coefficients of $2^{\text {nd }}, 3^{\text {rd }}$ and $4^{\text {th }}$ terms in the expansion of $(1+x)^n$ are in A.P, then the value of $n=$

• A

  6
• Correct answer
  B

  7
• C

  8
• D

  9

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