Three balls are drawn from a collection of 7 white, 12 green and 4 red balls The probability that each is of different colures is

• A

  $\frac{{}^7{C}_1\times {}^{12}{C}_1\times {}^4{C}_1}{{}^{23}{C}_3}$

• B

  $\frac{8}{253}$

• C

  $\frac{4}{253}$

• D

  $\frac{1}{253}$