Final answer:
Elena's sequence of transformations to demonstrate similarity involved a dilation from point D with a scale factor of 2, followed by a reflection over a vertical line through D.
Step-by-step explanation:
The question concerns the sequence of geometric transformations that Elena applied to demonstrate that two figures are similar. The sequence was a dilation using D as the center with a scale factor of 2, followed by a reflection over a vertical line through D.
Geometric transformations often include rotations, reflections, dilations, and translations. These transformations can change a figure's position and size while preserving its shape and proportionality, which are crucial characteristics for establishing similarity between figures