19. As shown in the figure, in $\triangle A B C$, $\angle A B C=90^{\circ}, A B=B C$, the vertices of the triangle lie on three mutually parallel lines $l_{1}, l_{2}, l_{3}$, and the distance between $l_{1}, l_{2}$ is $2$, the distance between $l_{2}, l_{3}$ is 3, the length of $A C$ is ( ).
A. $\sqrt{34}$
B. $2 \sqrt{34}$
C. $2 \sqrt{17}$
D. 34
Answer: $\mathrm{C}$