As you can see in the picture, all the points lie on the same line, so they are collinear. The line follows an equation with the general form of:
y = mx + b
where m and b are the constants
The b parameter is the y-intercept. This is the point at which the line intersects the y-axis. From the graph, b = 0. The other constant is the slope m. You can choose any two points, the answer would just be the same.
m = (y₂ - y₁)/(x₂ - x₁)
Suppose point 1 is (2,1) and point 2 is (3,1.5).
m = (1.5 - 1)/(3 - 2) = 1/2 or 0.5
Therefore, the answer is either 0 or 0.5. From the choices, the answer would be letter C.
