All these four communication improvements have meant a turning point when they were developed. On the other hand, the rejected option is not a communication improvement but an improvement in production and manufacturing activities. Assembly lines were also a turning point as they allowed to produce very large amounts of output, to reduce costs and to gain efficiency in production also due to reaching economies of scale.
The telephone, telegraph, mail delivery, and Trans-Atlantic Cable were all technologies for communication. The assembly line was not, it had nothing to do with communication, therefore that one does not belong, leaving you with the other four.
These qualities are understood as paying attention to humanity. These are key aspects if people plan to be tolerant of others and respect each other as human beings and if they are to co-exist in a peaceful and respectful way. These are all important for developing the society.
