The correct answer is: C. monopsony
A monopsony is a market structure in which there is only one buyer of a good or service. In the case of the farmer, the agricultural marketing board is the only buyer of his product. This means that the board has a lot of power over the price that it pays the farmer for his product. The farmer has no other choice but to sell to the board, even if the price is not what he would like.
A monopoly is a market structure in which there is only one seller of a good or service. In this case, the farmer would be the only seller of his product. This would give him a lot of power over the price that he charges for his product. However, in the case of the farmer, he is not the only seller of his product. There are other farmers who are also selling their products to the agricultural marketing board. This means that the farmer does not have as much power over the price that he charges for his product.
An oligopoly is a market structure in which there are a few large sellers of a good or service. In this case, there would be a few large farmers who are selling their products to the agricultural marketing board. This would give the farmers some power over the price that they charge for their product, but not as much power as they would have if they were the only sellers of their product.
A duopoly is a market structure in which there are only two sellers of a good or service. In this case, there would be only two farmers who are selling their products to the agricultural marketing board. This would give the farmers even less power over the price that they charge for their product than they would have in an oligopoly.