The correct answer is C. 120m.
The minimum stopping sight distance (SSD) is the distance required for a driver to see an obstacle, react to it, and stop safely. It is calculated based on the following factors:
- The driver’s reaction time, which is typically 2.5 seconds.
- The braking distance, which is the distance it takes the vehicle to stop after the driver applies the brakes.
- The road conditions, such as the presence of curves or hills.
For a two-lane, two-way road, the SSD is typically 120 meters. This means that if a driver sees an obstacle 120 meters away, they should be able to stop safely before hitting it.
Option A is incorrect because it is the distance required for a driver to see an obstacle and react to it. Option B is incorrect because it is the distance required for a vehicle to stop after the driver applies the brakes. Option D is incorrect because it is the distance required for a driver to see an obstacle, react to it, and stop safely on a one-lane road.