#### Answer

$\bf graph(d)$

#### Work Step by Step

Given: $x^2-6x+8=0$
Need to use factorization to solve the quadratic equation.
This can be factorized as follows:
$x^2-2x-4x+8=0$
or, $(x-2)(x-4)=0$
Now $x-2=0$ and $x-4=0$
Roots are $x=2,4$.
These values are represented by $\bf graph(d)$