Quaternary activities are related to intellectual services and involve research, development, and the production of information. These activities are centered around innovation, high-tech services, education, and research that help in solving problems and developing new technologies.
- Option (A) is incorrect because the extraction of minerals is related to primary activities, not quaternary activities.
- Option (B) is incorrect because increasing the value of raw materials into finished products is characteristic of secondary activities, not quaternary.
- Option (C) is correct because quaternary activities focus on research and development, which are fundamental to the growth of knowledge-based industries.
- Option (D) is incorrect as quaternary activities are not directly related to serving all people of society in a general sense, but more focused on specialized knowledge and services.
Thus, the correct answer is (C) It is concerned with research and development.
If \(\begin{vmatrix} 2x & 3 \\ x & -8 \\ \end{vmatrix} = 0\), then the value of \(x\) is: