Explanation:

- Primary Sector: Involves extraction and production of raw materials, like agriculture, mining, and fishing.

- Secondary Sector: Concerns manufacturing and processing, transforming raw materials into products.

- Tertiary Sector: Encompasses services like retail, entertainment, and financial services.

- Both Secondary and Tertiary: Involves activities touching both manufacturing and services, although real estate does not typically fit this combination.

Real estate primarily involves services such as marketing and management of properties, locating within the tertiary sector.

Your answer is: OPTION 2 - TERTIARY