Concept:Value is added to primary products when they are transformed or refined into finished or semi-finished goods.
Explanation:Primary products are raw materials obtained directly from nature, such as crops, minerals, fish, and timber.
These raw materials usually have low market value in their original state.
The processing industry converts them into usable goods, such as turning cocoa beans into chocolate or crude oil into petrol.
This transformation increases the product's usefulness and market price, thereby adding more value.
The mining industry only extracts minerals, while the construction and service industries do not directly add value to primary products.
Answer:The correct option is D. Processing industry.