The correct answer is: D. normal goods.
Normal goods are goods whose demand increases when income increases. This is because people tend to buy more of these goods when they have more money to spend. For example, if you get a raise at work, you might decide to buy a new car or take a vacation.
Inferior goods are goods whose demand decreases when income increases. This is because people tend to buy less of these goods when they have more money to spend. For example, if you get a raise at work, you might decide to eat out less often or buy cheaper clothes.
Capital goods are goods that are used to produce other goods. For example, a factory is a capital good that is used to produce cars. The demand for capital goods is not directly affected by changes in income.
Giffen goods are a type of inferior good that is so essential to people’s survival that they will actually buy more of it even when their income decreases. For example, if the price of bread goes up, people might actually buy more bread because they need it to survive.
In conclusion, the correct answer is D. normal goods.