The sum of $n$ terms of the following series $1 \cdot 2 + 2 \cdot 3 + 3 \cdot 4 + 4 \cdot 5 + \dots$ is:

  • A
    $n^3$
  • B
    $\frac{1}{3}n(n + 1)(n + 2)$
  • C
    $\frac{1}{6}n(n + 1)(n + 2)$
  • D
    $\frac{1}{3}n(n + 1)(2n + 1)$

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