The correct answer is: A. complementary goods.
Complementary goods are goods that are used together to satisfy a want. For example, a car and gasoline are complementary goods. You cannot use a car without gasoline, and you cannot use gasoline without a car.
Substitute goods are goods that can be used in place of each other to satisfy a want. For example, coffee and tea are substitute goods. You can drink coffee or tea to wake up in the morning.
Inferior goods are goods that people demand less of as their income increases. For example, as people get richer, they tend to buy less cheap clothes and more expensive clothes.
Abnormal goods are goods that people demand more of as their income decreases. For example, as people get poorer, they may buy more rice and less meat.