Legal Question in Business Law in California

Generally speaking, yes. A single corporation can have any number of divisions or departments, each operating a different "business" that is still part of the same corporation. More often, larger and more sophisticated multiple-line-of-business enterprises are set up with a system of separate corporations that are subsidiaries of the main (parent) corporation. However, this is done as a matter of liability limitation or for tax reasons or corporate identity purposes, and could be handled under a single corporation. I'd say that smaller businesses that can't afford the extra corporate franchise fees and accounting expense are more likely to operate their separate business lines under a single corporate entity than are larger companies which can afford the overhead expense associated with a more complex structure of multiple corporate entities (parent and subsidiaries). Either way works. The choice depends upon what's more practical for the particular enterprise.