This is a third degree equation since the largest exponent is 3. If the degree of the equation is odd then the graph starts up and ends down or starts down and ends up. (The opposite is true... if the degree of the equation is even then, like a parabola, the graph starts AND ends either both up or both down.).
Look at the term of the degree exponent... In this case -x^3. If the term is negative, as in this case, the graph starts in at the top left. (Conversely, if it were positive, it would start left bottom.)
We are now left with A,D,and E. See how a&e have just 2 bumps while d has4 bumps? The number of bumps is one less than the degree of the equation (unless there are no x^2 or x terms. So a & e are the correct answer while d would be x^5
