The primary reason Henry Ford was able to produce an affordable car is:
3. He developed a less expensive method of production.
Henry Ford revolutionized the automotive industry by introducing the assembly line, which significantly reduced production costs and time. This method allowed for mass production of vehicles, resulting in lower prices for consumers. While options 1, 2, and 4 did play roles in the broader context of car sales and manufacturing, the key factor in making the car affordable was Ford's innovative production techniques.