Final answer:
Congruent chords subtend equal angles in a circle.
Step-by-step explanation:
In a circle, the various relationships between the lengths of the chords and the angles can be described using the concept of congruent chords and subtended angles. When two chords, EC and BD, intersect at point A, if the chords are congruent, meaning they have the same length, then the angles they subtend at the center of the circle are also equal. This relationship is described as congruent chords subtending equal angles. Therefore, the answer is option D) Congruent chords / subtend equal angles / are proportional.