The answer is d: Ford's revolution of the assembly line to make cars less expensive.
although they saw he invented the assembly line he did not it was in fact Ransom E. Olds who did. all that Ford did was improve it. he put a person to do one thing and that was what they did nothing else. this made it faster as to this had nobody fighting to do the job with the person they were working with.
In history ??? Or something else
