In geometry, what effect does a reflection have on the orientation of an object?

A reflection in geometry involves flipping an object across a line, which is known as the line of reflection. This action has a specific impact on the orientation of the object. When an object is reflected, the order of its points is reversed. For instance, if you consider the orientation of the letters in a word, when reflected, the leftmost point is now on the right, and the rightmost point is now on the left. This is why the correct answer indicates that a reflection reverses the orientation of an object.

By contrast, the other options imply different effects that are not characteristic of reflections. Maintaining the original orientation would not accurately describe what happens in a reflection, as the object indeed appears reversed. Flipping the object upside down suggests a rotation or a different type of transformation rather than a straight reflection. Similarly, rotating the object 180 degrees changes its orientation, but that is distinct from reflection, which specifically involves flipping over a line without any rotational movement involved. Therefore, the effect of reflection is correctly understood as a reversal of orientation.