Answer: DE (second choice)
Segment DE, which is the same as segment ED, goes through the center point O. All diameters must go through the center of a circle. Also, the endpoints of any diameter are on the circle's edge.
Put another way, a diameter is a chord that goes through the center. A chord is any segment with its endpoints on the circle. For instance, segment BC is a chord but it is not a diameter since it doesn't go through the center.
