Concept: Marketing boards are set up mainly to protect farmers from unstable export prices.
Explanation:Cash crop prices in international markets often fluctuate sharply.
Marketing boards buy the crops from farmers at fixed or stable prices.
This stabilizes the incomes of cash crop farmers even when world prices fall.
Therefore, the main objective is not to raise government revenue, train farmers, or provide storage alone.
It is to steady producer prices and incomes.
Answer: C. stabilize the incomes of cash crop farmers