A marketing firm that sells advice to clients belongs to which industry?

• A. Tertiary
• B. Primary
• C. Quaternary
• D. Secondary

Answer: (A)

The main idea here is recognizing how economies classify activity by what is produced. A marketing firm that sells advice delivers a service rather than a physical product. The sector that groups these kinds of activities—providing intangibles like advice, consulting, and customer support—is the service sector, often called the tertiary industry. It contrasts with the primary sector, which involves extracting natural resources (like farming or mining), and the secondary sector, which covers manufacturing and turning inputs into goods. The quaternary sector refers to knowledge-based activities such as research and information processing; while marketing advice has a knowledge element, it is traditionally categorized with general services in the tertiary sector.