The correct answer is: C. Both A and B
Complementary goods are goods that are used together. For example, pens and paper are complementary goods. If the price of pens decreases, people will buy more pens. This will increase the demand for paper, as people will need more paper to use with their new pens. Therefore, the demand for complementary goods is inversely related to their price.
Substitute goods are goods that can be used in place of each other. For example, coffee and tea are substitute goods. If the price of coffee increases, people will buy less coffee. This will increase the demand for tea, as people will switch to drinking tea instead of coffee. Therefore, the demand for substitute goods is directly related to their price.
In conclusion, both A and B are incorrect statements. The demand for complementary goods is inversely related to their price, while the demand for substitute goods is directly related to their price.