Answer:
E'F' and EF are equal in length.
Explanation:
A 'reflection across the x-axis' is a type of rough transformation.
Rough transformations are types of transformations where the pre-image and image do not change their size, and therefore congruent to each other.
The x-coordinate in a pre-image would remain the same, but the y-coordinate would become the opposite.
E'F' and EF should be equal in length.