Trapezoid A B C D is shifted down and to the left to form trapezoid A prime B prime C prime D prime. Trapezoid A prime B prime C prime D prime is rotated 270 degrees about point B.
What is the final transformation in the composition of transformations that maps pre-image ABCD to image A"B'C"D"?
a translation down and to the right
a translation up and to the right
a 270° rotation about point B'
a 180° rotation about point B'