Final answer:
Paper is the largest source of municipal solid waste in the United States, primarily because of its extensive use in various products and packaging. Items like cardboard and newspapers contribute to this category, which surpasses other materials such as plastics, metals, and food scraps in volume.
Step-by-step explanation:
The largest source of municipal solid waste in the United States is C. Paper. Municipal solid waste (MSW) comprises various materials discarded from residential, commercial, and industrial sources. Among these materials, paper waste generally forms the largest component, including items like cardboard, newspapers, and other paper products. This is mainly due to the widespread use of paper in packaging, printing, and many other daily activities. While recycling programs help mitigate the impact of paper waste, reducing the use of paper and opting for digital alternatives can also significantly decrease the amount of paper entering the waste stream.
Food scraps are also a notable portion of the municipal solid waste, but do not surpass paper in volume. Plastics and metals are valuable in the recycling market; however, from an energy and resource standpoint, the recycling of metals, especially aluminum, is more effective compared to plastics, which present some challenges in recycling efficiency and energy consumption.