With increase in speed of the traffic stream, the minimum spacing of vehicles

With an increase in the speed of the traffic stream, the minimum spacing of vehicles increases because higher speeds require greater stopping distances and reaction times for safety.

At low speeds, vehicles can maintain shorter gaps due to shorter stopping distances. However, as speed increases, drivers must maintain longer gaps to avoid collisions.

Option B is incorrect as spacing cannot decrease with speed due to safety risks.

Option C is incorrect because there is no minimum spacing point after which spacing increases again—spacing increases consistently with speed.

Option D is incorrect since spacing does not decrease after reaching a maximum—it continues to increase or is maintained.

Thus, only Option A correctly reflects the direct relationship between speed and minimum vehicle spacing.