A producer who can only influence the price of his product but canNOT determine the quantity to be sold is referred to as

A producer who can influence the price of a product but cannot determine the quantity to be sold is best described as a monopolist.

Here's an explanation:

In a monopoly, there is only one producer or seller who dominates the entire market for a particular product or service. This producer has the power to influence the price because they are the sole supplier, and there are no close substitutes. However, while they can set the price based on their objectives, the actual quantity sold is determined by the market demand at that specific price.

The other terms are different:

• Duopoly refers to a market structure where there are two dominant producers. Here, each producer needs to consider the other's actions before setting prices or quantities.
• Monopsonist is a scenario where there is only one buyer, not one seller.
• Oligopoly refers to a market structure where a small number of firms have significant control. Firms in an oligopoly influence prices but must consider the reactions of other firms.