A

B. The two economic laws exist in theory. They work in practice, but real world factors can have an effect.

Explanation:

The law of supply and demand is used to explain interactions between the buyers and the sellers from the perspectives of some resource. This law is illustrated in the graph below. It states that, for example, if the price of goods increased, the quality of demand would drop.

However, real factors can affect this law and make it obsolete. For instance, if a hurricane occurred in some area and destroyed the majority of stores that sold food, the demand would remain high even if the remaining stores raised prices for food significantly.

Law of supply and demand graph.
Law of supply and demand (Source: quickonomics.com)