Which one of the following activities is related to quaternary sector?

The correct answer is option 3: University teaching

The quaternary sector is a specialized segment of the economy that focuses on the knowledge-based services. It is often considered an extension of the tertiary (service) sector but is distinguished by its high degree of intellectual expertise.

University teaching — Correct, because education and knowledge-based services are part of the quaternary sector.

NCERT: "The Quaternary Sector along with the Tertiary Sector has replaced most of the primary and secondary employment as the basis for economic growth. Over half of all workers In developed economies are in the ‘Knowledge Sector’ and there has been a very high growth in demand for and consumption of information based services from mutual fund managers to tax consultants, software developers and statisticians. Personnel working in office buildings, elementary schools and university classrooms, hospitals and doctors’ offices, theatres, accounting and brokerage firms all belong to this category of services."