$r$ and $n$ are positive integers $r>1, n>2$ and coefficient of $(r+2)^{\text {th }}$ term and $3 r^{\text {th }}$ term in the expansion of $(1+x)^{2 n}$ are equal, then $n$ equals

• A

  3r
• B

  3r + 1
• Correct answer
  C

  2r
• D

  2r + 1

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