A 90° rotation about the origin is followed by a reflection across the line y = -x, transforming a point (x, y) to (-y, x).
The question asks what transformation follows a rotation of 90° about the origin. To understand this transformation, consider the effect of the rotation on the coordinates of any point. After a 90° rotation about the origin, a point (x, y) is transformed to the point (-y, x). This transformation is equivalent to reflecting the point over the line y = -x. Therefore, this rotation is followed by a reflection across the line y = -x.