First, we look at where the equation intersects the y axis. It intersects at y = 4, which means that in the end of the equation there must be a "+4", so we can rule out the first two.
Second, we look at the slope of the line. Slope is defined as rise over run. As you can see in the graph, the line moves up 2 units while moving right 3 units. That means the coefficient of x (which is the slope) will be 2/3, which means the answer is y = 2/3x + 4.
