Concept:Solid mineral exploitation adds new revenue sources, which reduces over-dependence on a single export.
Explanation:Developing countries often rely on one main export, such as oil or cash crops.
This makes their revenue unstable when prices fall.
Developing solid minerals creates another major income earner.
This is called economic diversification.
Diversification stabilizes government revenue by balancing losses in one sector with gains from another.
It does not promote a mono-economy, and technology transfer or energy provision are not the main reasons for revenue stability.
Answer:C. the diversification of the economy.