A stone is whirled in a vertical circle at the end of a string. When the stone is at the highest position, the tension in the string is:

Explanation

When a stone is whirled in a vertical circle at the end of a string, the tension in the string varies depending on the stone's position in the circle. At the highest position, the tension is at its minimum because the stone is just moving fast enough to maintain circular motion. This occurs when the tension and the weight of the stone are in opposite directions but balanced to keep the stone in its circular path. Options B, C, and D are incorrect because they do not accurately reflect the relationship between tension and the stone's position in a vertical circle.