Consider that y' is the slop of the function, and if y'=x^2y then the slope = 0 along both the x-axis and y-axis. Graph 1 doesn't fit that criteria. Also as x gets bigger and/or as y gets bigger the slope becomes larger magnitude - always positive for y>0 and always negatiove for y<0. So now, take another look at the 5 graphs and see which one fits the bill.
Well, graph II does meet the first two criteria - that the slope is zero along the x- and y-axes and the magnitude of the slope gets bigger with increasing values of x and y. But does it meet the other criteria - is the slope always positive for y>0 and always negative for y<0?