________ add value to natural resources by transforming raw materials into valuable products.

The correct option is Secondary activities.

Step-by-step Explanation:

1. Understanding Economic Sectors:
Economic activities are broadly classified into different sectors based on the nature of the work:

• Primary activities: Involve the direct extraction and production of natural resources (e.g., agriculture, mining, fishing, forestry).
• Secondary activities: Involve processing, manufacturing, and transforming raw materials harvested in primary activities into finished, higher-value goods (e.g., turning iron ore into steel, weaving cotton into cloth, or processing wood into paper).
• Tertiary activities: Provide support and services to the primary and secondary sectors (e.g., transport, banking, trade, education).
• Quaternary activities: Focus on knowledge-based services, information sharing, research, and development.
• Quinary activities: Represent the highest level of decision-making and policy formation (e.g., key government officials, scientific researchers).

2. Adding Value to Resources:
Raw materials direct from nature often have limited utility or lower value on their own. When a manufacturing unit or industry processes these raw materials (primary products) through various stages of production, they convert them into finished goods that are more useful and hold higher market value. For example, wood (raw material) has less value compared to the furniture (valuable product) made from it.

3. Conclusion:
Since the process of transforming raw materials into finished, valuable products defines manufacturing and processing, it falls directly under Secondary activities. Therefore, secondary activities add value to natural resources.