The correct answer is B. Complements
Explanation:
In economics and related, the term "complements" is used to describe products or services that are closely related as these are often consumed together. Due to this, the increase or decrease in demand, supply or price will often affect complements similarly.
This concept applies to milk and cereal because many people consume these two products together; also, an increase in the price of one causes a decrease in the demand of the other as people are less likely to buy cereal if milk is more expensive and vice versa. Thus, the two products are complements.
