A random variable X has a probability distribution P(X) of the following form, wher K is some unknown constant : $P(X-x_i)=\left\{\begin{matrix}2K& , if\, x_i= 0\\Kx_i & , if \, x_i =1\\K(x_i-1) & ,if\, x_i = 2 \, or \, 3\\0& , otherwise\end{matrix}\right.$ The value of K is :

$\frac{1}{4}$ $\frac{1}{6}$ $\frac{2}{3}$ 6

$\frac{1}{6}$