Final answer:
The tertiary sector is the most knowledge-intensive economic sector, offering services such as healthcare and education, while the primary sector, focused on raw materials, is the least knowledge-intensive.
Step-by-step explanation:
The most knowledge-intensive economic sector is the tertiary sector, which includes services such as healthcare, education, and money management. The quaternary sector is also knowledge-intensive as it involves the management of information, research and development, and other high-level services. In contrast, the primary sector is the least knowledge-intensive, as it revolves around the extraction and production of raw materials like metals and crops. Therefore, the correct answer to the question is B) Tertiary sector; Secondary sector.