Why did it become necessary to mass produce and improve the quality of milk?

The necessity to mass produce and improve the quality of milk is closely tied to the movement of population to cities. As urban areas expanded due to industrialization and population growth, the demand for dairy products increased significantly. With more people living in cities, there was a greater need for a reliable and consistent supply of milk to meet the nutritional needs of the urban population. This shift in demographics prompted the dairy industry to adopt mass production techniques to ensure that milk could be delivered efficiently and in sufficient quantities to urban markets.

In conjunction with this demographic shift, the quality of milk also became a priority to satisfy consumer expectations and health standards. Health regulations and consumer awareness about the importance of food safety further drove the improvements in quality. Therefore, the urban migration not only increased demand but also influenced how milk was produced and marketed.

The other options do not fully capture the primary reasons for the necessity of mass production and quality improvement in milk. While advancements in dairy farming technology and rising animal welfare standards have contributed to enhancing milk production and quality, they are not the principal driving forces compared to the demand generated by urbanization. A decrease in milk demand is contrary to the context of the question, as it would not necessitate improvements in production.