What problem may have caused the vikings to stop coming to north america?
a) battles with native americans
b) lack of food
c) inability to build houses
d) bad weather

Most likely reason why the Vikings stopped coming to North America was because a lack of food - B. It is often accredited that the Vikings that settled in Greenland and inhabitate those areas, until a massive crop failure happened where they were not able to susatin themselves with the food which they produced anymore, they stayed on Greenland. After that, however, they left. 

The answer is decreasing soil fertility