A downward sloping demand curve means that as the price of a good decreases, the quantity demanded of that good increases. In other words, there is an inverse relationship between the price of a good and the quantity of that good demanded by consumers. This is the fundamental law of demand in economics.
As the price of a good decreases, consumers are more willing and able to purchase it, which leads to a higher quantity demanded. Conversely, as the price of a good increases, consumers are less willing and able to purchase it, which leads to a lower quantity demanded.
Therefore, the correct answer is - price must be lowered to sell more of the good. Total revenue may increase or decrease as the price changes depending on the magnitude of the change in price and quantity demanded.