Answer:
option C.
Step-by-step explanation:
According to equidistant chords theorem, two chords of a circle are congruent if and only if they are equidistant from the center of the circle.
Congruent means they are equal in length.
Using equidistant chords theorem, we can fill the blank.
In a circle, two chords that are equidistant from the center of the circle are always equal in length.
Therefore, the correct option is C.
