The graph below shows the price, y, in dollars, of different amounts of granola, x, in pounds:

A graph titled Granola Prices shows Number of Pounds on x axis and Price in dollars on y axis. The scale on the x axis shows numbers from 0 to 12 at increments of 2, and the scale on the y axis shows numbers from 0 to 48 at increments of 8. A straight line joins the ordered pairs 0, 0 and 12, 48

Which equation best represents the relationship between x and y?

y = 8x
y = x + 4
y = 4x
y = x + 8