Which transformation changes the orientation of a shape?

A reflection is a transformation that changes the orientation of a shape. When a shape is reflected across a line (the line of reflection), each point of the shape is flipped to the opposite side of that line. This repositions the points of the shape so that the overall arrangement is reversed, thereby changing the orientation. For instance, if a shape appears one way before the reflection, it will appear as a mirror image after the transformation, indicating a clear alteration in orientation.

In contrast, both translations and rotations preserve the orientation of a shape. A translation moves a shape without altering its size, shape, or orientation, maintaining the relative positions of the points. A rotation turns a shape around a fixed point but does so without changing the arrangement of the shape's points relative to each other, hence keeping the orientation intact. Scaling changes the size of a shape but does not affect its orientation either. Thus, it is the reflection transformation that distinctly alters the orientation by reversing the arrangement of points relative to the line of reflection.