D is the center of the circle.
Any point from D to the circumference of the circle is the radius of the circle.
• DA is a radius
,
• DB is a radius as well
,
• DC is a radius
CB is not a radius. It goes from a point in the circumference to the opposite point of the circumference, through the center. It is a diameter.
Thus,
CB is not a radius.
Answer
CB