Answer:
B. [tex]4\pi[/tex]
Step-by-step explanation:
[tex]\mathsf{arc \ length=\dfrac{2\pi r\theta}{360}}[/tex]
(where [tex]\theta[/tex] is the angle of the sector measured in degrees and r is the radius)
[tex]\implies \mathsf{arc \ length=\dfrac{2\pi \cdot 18 \cdot 40}{360}=\dfrac{1440\pi}{360}=4\pi}[/tex]
