The correct answer is C. financial services corporations.
A financial services corporation is a type of conglomerate that combines many financial institutions within a single corporation. These corporations typically offer a wide range of financial services, such as banking, insurance, and investment management.
Preferred service corporations are corporations that are formed to provide specific services to a particular group of people, such as employees of a particular company or members of a particular organization.
Commercial service corporations are corporations that are formed to provide general commercial services, such as retail sales or transportation.
Common service corporations are corporations that are formed to provide a variety of services to the general public, such as utilities or telecommunications companies.