What are typical byproducts of the refining process?

The refining process of crude oil primarily yields various byproducts, notably asphalt, sulfur, and several industrial chemicals. Asphalt is produced as a residue from the distillation of crude oil and is widely used in road construction and roofing. Sulfur is a valuable byproduct that often comes from the desulfurization of petroleum products, especially given the environmental regulations regarding sulfur content in fuels. Industrial chemicals are also derived from refining, including petrochemicals that serve as building blocks for a multitude of products ranging from plastics to solvents.

In contrast, other options list items unrelated or minimally related to the refining process. For instance, plastic and glass are processed products that result from petrochemicals and other raw materials but are not direct byproducts of refining. Natural gas and coal are energy sources that can be relevant in a broader energy context but do not typically come from the oil refining process. Water and salt might be present in some contexts, but they are not significant byproducts associated with refining crude oil. Thus, the choice of asphalt, sulfur, and industrial chemicals accurately reflects the expected outputs from the refining operations.