Which is the longest straight stretch of road in the world?

a) Eyre Highway, Australia

b) ND-46 W, United States

c) B71, Australia

d) Highway 10, Saudi Arabia 

Highway 10 in Saudi Arabia is the longest straight stretch of road in the world. It has a straight stretch of 256 km length. This road starts from Haradh and ends at Al Batha and cuts through Rub Al-Khali desert.