How is a transformation reflected over a line expressed algebraically?

The correct answer is based on the fact that reflecting a transformation over a line involves specific coordinate changes that depend on the properties of the line, such as its slope and intercept. When reflecting a point or a shape over a line, each point needs to be moved perpendicularly to the line, and its new coordinates can be calculated based on a formula involving the line's equation.

For example, if you have a line given in the slope-intercept form (y = mx + b), the reflection can be determined by calculating the angle of incidence and using the perpendicular distance from the point to the line. This results in new coordinates that represent the transformed shape after reflection. The algebraic representation of this transformation focuses on these coordinate adjustments rather than merely listing the vertices or altering dimensions.

Other options are not suitable because they focus on aspects that do not directly relate to the algebraic nature of reflections. For instance, using the coordinates of all vertices does not explain how to perform the transformation itself; rather, it assumes you already have points to start with. Changing the length of the shape pertains more to dilation transformations rather than reflections. Using angle measurements is also unrelated, as it does not adequately capture the process of reflecting a transformation algebraically over a line.