Answer:
A
Explanation:
We plot the points (x,y) in the coordinate system and the points are shown in the diagram attached.
We can draw a line y = -6 connecting the RED and BLUE points. Also, we can draw a line x = 9 connecting the BLUE and GREEN points.
The intersection of these two PERPENDICULAR LINES is at the point (9, -6) (as seen --- The blue point). So, when two perpendicular lines intersect, that point is a right angle.
So, the 3 points given INDEED make a right triangle.
So, correct answer is A