Which of the following sentences is written correctly?

A. Although he didn’t invent the automobile, Henry Ford developed affordable vehicles that could be mass-produced.

B. Their were so many people who wanted the vehicles that Henry Ford built a larger factory in highland park Michigan.

C. When was the assembly line with conveyor belts first used to assemble the vehicles.

D. Cars aloud people to move away from cities that were filthy with manure from horses.

E. The cars on the road was less dangerous then the horses in the city that trampled people and caused accidents.