Answer:

The correct answer is option 'B', i.e., distance travelled.

Explanation:

- The speed-time graph represents the relationship between speed and time for a particular object or body in motion.
- The area under the speed-time graph corresponds to the distance travelled by the object.
- In a speed-time graph, the speed is represented on the y-axis (vertical axis) and time is represented on the x-axis (horizontal axis).
- The area under the graph can be calculated by dividing the graph into different shapes (rectangles, triangles, etc.) and then calculating the area of each shape.
- Each shape represents a specific time interval and the speed within that interval.
- By summing up the areas of all the shapes, we can determine the total distance travelled by the object.
- For example, if the speed-time graph shows a constant speed of 10 m/s for a duration of 5 seconds, the area under the graph would be a rectangle with a base of 5 seconds and a height of 10 m/s. The area would be equal to 5 seconds * 10 m/s = 50 meters, which represents the total distance travelled by the object.
- Therefore, the quantity measured by the area occupied under the speed-time graph is the distance travelled by the object.

Key Points:
- Speed-time graph represents the relationship between speed and time.
- Area under the speed-time graph corresponds to distance travelled.
- The area can be calculated by dividing the graph into different shapes and calculating their areas.
- Summing up the areas of all shapes gives the total distance travelled by the object.