Question

what is the line called over which an object is flipped during a reflection?
line of reflection
axis of rotation
line of translation
line of symmetry

Explanation:

The question asks for the name of the line over which an object is flipped in a reflection. The provided visual explicitly labels this line, and the term matches the correct definition of the line used for reflection transformations. Other options refer to different geometric transformations: rotation uses an axis of rotation, translation uses no fixed line, and line of symmetry is a related but distinct concept about balanced shapes, not the line of flipping for a reflection.

Answer:

Line of reflection