Deaths by traffic accident are more likely to occur in a. high-income countries b. middle-income countries c. low-income countries d. poor countries

I would say that deaths by traffic accidents are more likely to occur in both high and middle income countries where more people can have vehicles whereas in poor countries many people will not have a car and will have to travel by either mass transit in the city or bus or train in the country. 

B. Middle income! (:

Europeans are more concentrated in urban areas.