Henry Ford's Most Distinctive Contribution to the Automobile Industry Was

Henry Ford's most distinctive contribution to the automobile industry was

A) installment credit buying of cars.
B) voluntarily permitting unions to organize in his auto plants and agreeing to negotiate a union contract with the United Auto Workers (UAW) over wages, benefits, and worker safety issues.
C) introducing a variety of automobile models with varied colors and styles.
D) design changes that improved speed.
E) production of a standardized, relatively inexpensive automobile.