Concept:Transportation systems are affected by natural and human factors that reduce safety and efficiency.
Explanation:Poor visibility is a major operational problem in world transportation.
It affects air and ocean transport especially when fog, mist, or heavy cloud forms in the atmosphere.
Poor visibility reduces the ability of pilots and ship captains to see other craft, runways, or navigational lights.
This can cause delays, disrupt routes, and increase the risk of accidents.
The other options are not transportation problems because they are natural geographic conditions, not obstacles to movement.
Therefore, the correct choice is poor visibility.
Answer:D. poor visibility.