Figure ABCD is a trapezoid. Which sequence of transformations will carry figure ABCD onto itself?

a reflection across side b followed by a 180° rotation about point A

a reflection across side b followed by a 360° rotation about point A

a reflection across the line joining the midpoints of DA and CB followed by a 180° rotation about the midpoint of DA

a reflection across the line joining the midpoints of DA and CB followed by a second reflection about the line joining the midpoints of DA and CB