The correct answer is "A".
A factory system is a method of manufacturing which uses a combination of machinery and division of labor. Division of labor is the separation of tasks in a given production process. This will eventually create workers who are specialized in performing a certain task.
As the industrial revolution kept on gathering pace, urban areas started to develop as people moved to towns which were located near the factories where they were employed or searching for employment. It was common to see that people lived at a walking distance from their work sites.