The correct option is
B OB: Radius; AC: Diameter; AD: Chord
The given figure of the path in which the horse moves is:
![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/1541711/original_Capture03.PNG)
From the figure, we can observe that O is the centre of the circular path, and A, B, C, and D are the poles on the path.
After joining the points, we observe that
⇒ OB is the radius of the circle, O is the centre, and B is a point on the circumference of the circle.
⇒AC is the line passing through the centre of the circle, and both its ends are on the circumference of the circle. It means that AC is the diameter of the circle.
⇒ AD is also a line whose ends are on the circumference of the circle, but it does not pass through the centre. This means that AD is a chord of the circle.
Hence OB, AC, and AD are the radius, diameter, and chord of the circular path respectively.