The correct answer is A. demand was entirely inelastic.
Demand is inelastic when a change in price has little or no effect on the quantity demanded. In other words, consumers are not very responsive to changes in price. This can happen for a number of reasons, such as when the good is a necessity, when there are few substitutes available, or when consumers have a strong preference for a particular brand or type of good.
If there were no changes in the quantity of food sold even when its price falls, we would know that demand for food was entirely inelastic. This would mean that consumers are not at all responsive to changes in the price of food. They would continue to buy the same amount of food, regardless of the price.
This could be because food is a necessity. People need to eat, so they will continue to buy food even if the price goes up. It could also be because there are few substitutes for food. If the price of food goes up, people cannot simply switch to another good. They will still need to buy food, even if it is more expensive. Finally, it could be because people have a strong preference for a particular brand or type of food. Even if the price of their favorite food goes up, they will continue to buy it, rather than switching to a cheaper alternative.
Inelastic demand can be a problem for businesses. If they cannot raise prices without losing customers, they may not be able to make a profit. However, it can also be a good thing for consumers. If demand is inelastic, they will not have to worry about the price of goods going up, because they will still be able to afford them.