The coefficient of $x^r (0 \le r \le n - 1)$ in the expression :

$(x + 2)^{n-1} + (x + 2)^{n-2}. (x + 1) + (x + 2)^{n-3} . (x + 1)^2; + ...... + (x + 1)^{n-1}$ is :

  • A

    $^nC_r (2^r - 1)$

  • B

    $^nC_r (2^{n-r} - 1)$

  • C

    $^nC_r (2^r + 1)$

  • D

    $^nC_r (2^{n-r} + 1)$

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