Mashaal Masha
Line $p$ is defined by $2y+18x=9$. Line $r$ is perpendicular to line $p$ in the $xy$-plane. What is the slope of line $r$?
Difficulty: Medium
A: 

$-9$

B: 

$-\frac{1}{9}$

C: 

\(\frac{1}{9}\)

D: 

$9$