the answer would be the 3rd one, we find this by gettign our facts, first find our y-intercept, where does the line pass through the y line, it passes through the positive 4, now lets find the slope, the slpe is the rise over run, the graph rises 4 and runs 1 to the right, so your slope will be 4 now how do you know if its a positive or a negative, well if the graph rises to the right it is a positive and if it rises to the left is a negative... This graph rises to the right so our slope is a positive... SO our equations should look like f(x)=4x+4 and our 3rd option has exactly this answer, so your answer would be the 3rd one
Hope this helps