Final answer:
The correct answer is Option C. The slope of line r, perpendicular to line p (2y + 18x = 9), is 1/9.
Step-by-step explanation:
To find the slope of line r, which is perpendicular to line p, we first need to write line p in slope-intercept form (y = mx + b). The equation of line p given is 2y + 18x = 9. We can rearrange this to solve for y by subtracting 18x from both sides and then dividing by 2, resulting in y = -9x + 4.5. The slope (m) of line p is thus -9. Since line r is perpendicular to line p, its slope will be the negative reciprocal of -9, which is 1/9. Therefore, the correct answer is C. 1/9.