The equation that gives 8 for the value of x is

( option C)
In the equation , the value of x must satisfy the equation, this means that when we insert the value of x , the two sides must equate.
The equation in option D will give the value of x to be 8.
checking;

multiply all terms by 4
= 5x - 8 = 6x -16
5x - 6x = -16+8
-x = -8
x = 8
Therefore, the equation in option C will give x as 8.