Step-by-step explanation:
If the two chords are congruent, then they must be equidistant from the centre of the circle.
Answer: <u><em>D) They must be perpendicular</em></u>
A is rejected because the chord might not pass through the center of the circle.
B is rejected because the chords are not obligated to be parallel.
C is rejected because it is not compulsory for the chords to be perpendicular.