Final answer:
Due to eggs and cereal being substitute goods, a decrease in the supply of eggs caused by a disease would lead to an increase in the price of eggs, thus shifting the demand for cereal to the right as consumers seek alternatives.
Step-by-step explanation:
When two products are substitutes for one another, an increase in the price of one leads to an increase in the demand for the other. In this case, if a disease kills a large number of chickens, this will result in a decrease in the supply of eggs, likely causing the price of eggs to rise. As a result, consumers will look for alternatives for their breakfast choices, making cereal a more attractive option. Therefore, the demand for cereal will shift to the right, as consumers substitute away from eggs towards cereal due to the rise in the price of eggs.