What is the equation of the graphed line?

a. y=-5/2x

b. y=-2/5x

c. y=2/5x

d. y=5/2x

To find the equation of a graphed line, find its slope and y-intercept.
Slope is change in y over change in x. In other words, if the graph goes down, you find how much it goes down and how much it goes to the right. (and vice versa if the graph goes up.)
So just start from the origin and count how many down until there is a definite point above (y) and how many left or right to that point (x).
So with these two points, the slope is y/x

The graph of a line in slope intercept form is y = mx + b
M is slope, and b is y-intercept.
Since the graph intersects the origin there is no y-intercept.
So your equation is y = mx
(m is the slope you found)