Final answer:
The option that is not one of the four primary functional areas of a firm is 'legal'; the main areas include human resources, marketing, operations, and finance.
Step-by-step explanation:
The correct answer to the question is b) legal. The four primary functional areas of a firm typically include: human resources (dealing with recruitment, employee relations, and benefits), marketing (focusing on promoting and selling products or services), operations (overseeing the production of goods and service delivery), and finance (managing the company's financial resources). While the legal department is an essential part of many businesses, it is not typically categorized as one of the core functional areas, but rather as a support or ancillary function that helps the core areas comply with laws and regulations.