Answer:
Option D
Explanation:
Given c= (x-2) a +b and d= (2x+1) a-b are collinear
$\therefore$ c= $\lambda$ d
$\Rightarrow$ (x-2)a+b= $\lambda$ [(2x+1) a-b]
$\Rightarrow$ $\frac{x-2}{2x+1}=\frac{1}{-1}=\lambda$
$\Rightarrow$ 2x+1= -x+2
$\Rightarrow$ 3x=1
$\Rightarrow$ x= $\frac{1}{3}$
