1. D. Quantity demanded by consumers will decrease, quantity supplied by producers will decrease.
As the price of a good increases, people will be inclined to buy less of it, which means that the demand for the good will decrease. Once suppliers notice that the product is not as popular anymore, they will produce less, so as not to lose money. This means that the supply will similarly decrease.
2. C. strong control over price.
A monopoly refers to a situation in which only one producer controls the supply of a good or service. Also, the entry of new producers is highly restricted. Monopolists firms have the power to keep prices high and restrict the output.
3. B. law of demand.
In economics, the law of demand states that as the price of a good increases, the quantity demanded decreases. Conversely, as the price of a good decreases, quantity demanded increases. In this example, as the price of the shirt went up, the quantity demanded decreased, following the law of demand.