The expansion of ${(x + y + z)}^n$ is given by

• A

  $\sum \frac{n!}{p!q!r!}{x}^p{y}^q{z}^r$where $p,q,r\ge 0,p+q+r=n$

• B

  $\sum \frac{n!}{p!q!r!}{x}^p{y}^q{z}^r,$where $p+q+r=n$

• C

  $\sum \frac{(n+1)!}{p!q!r!}{x}^p{y}^q{z}^r,$where $p+q+r=n$

• D

  none of these