What is one of the functions of a Coker in a refinery?

A Coker in a refinery primarily serves to convert heavy fractions of crude oil into lighter, more marketable products. This process involves thermally cracking heavy residues into lighter hydrocarbons, resulting in the production of lighter fractions such as gasoline and diesel from heavy bottom feeds. The operation of the Coker allows for the efficient processing of heavy oil components that might otherwise be less valuable or economically challenging to refine.

While options such as improving the quality of heavy oil products and removing sulfur compounds are relevant to refinery processes, they do not specifically highlight the primary function of a Coker. The Coker's distinctive role is centered on upgrading heavier fractions by breaking them down into more useful lighter products, making option C the most accurate representation of its main function.