Answer: The correct option is (B) 2 units.
Step-by-step explanation: Given that the length of the line segment AB is 18 units.
We are to find the value of d, the distance between the tick marks on the number line.
From the figure, we note that
the line AB is divided into nine equal segments and one of them measures d units.
So, we must have
[tex]d\times9=AB\\\\\Rightarrow 9d=18\\\\\Rightarrow d=\dfrac{18}{9}\\\\\Rightarrow d=2.[/tex]
Thus, the value of d is 2 units.
Option (B) is CORRECT.
