What type of sorption involves the attachment of substances at the surface?

The correct answer pertains to adsorption, which is the process involving the attachment of molecules from a gas, liquid, or dissolved solid to a surface. During adsorption, these substances adhere to the surface rather than being absorbed into the material’s bulk.

This phenomenon can occur at various interfaces, such as between a solid and a gas or a solid and a liquid. The process is often characterized by the formation of a film on the surface, where the amount and rate of attachment can vary based on factors such as temperature, pressure, and the nature of the adsorbate and adsorbent.

In context, absorption is a distinctly different process, where a substance is taken up into the bulk of another material, resulting in a uniform distribution throughout the absorbing medium. Physisorption refers to a specific type of adsorption characterized by weak van der Waals forces, which may lead to a physical attachment at the surface but does not change the chemical nature of the substances involved. Endothermic sorption specifies a type of thermal process related to sorption that absorbs heat, which doesn't directly define the nature of the interaction at the surface.

Thus, adsorption is uniquely focused on the surface-level attachment of substances, making it the correct choice for the question posed.