Final answer:
Virtual memory is an extension of main memory, and a software developer works in the quaternary sector of an economy, which deals with knowledge and information-based services.
Step-by-step explanation:
Virtual memory uses disk space as an extension of main memory (b). It is a feature of an operating system that allows a computer to compensate for physical memory shortages, temporarily transferring data from random access memory (RAM) to disk storage. This process creates an illusion for users that there's almost unlimited RAM available, even though the computer is limited by physical RAM.
In response to your second question, someone working as a software developer would be in the quaternary sector (d) of an economy. This sector is characterized by intellectual services like knowledge-oriented economic activities—software development being a perfect example. It extends beyond the traditional primary (agriculture, mining), secondary (manufacturing), and tertiary (services) sectors.
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