The correct answer is: A. substitute goods.
Substitute goods are goods that can be used in place of each other. For example, coffee and tea are substitute goods, as people can drink either one to get their caffeine fix. If the price of coffee goes up, people may switch to drinking tea instead. This is because the relative price of coffee has increased, making it more expensive than tea. As a result, people will demand less coffee and more tea.
Abnormal goods are goods that have an inverse relationship between price and demand. This means that when the price of an abnormal good goes up, demand for the good actually goes up. This is because abnormal goods are considered to be luxury goods, and people are willing to pay more for them even if they are more expensive.
Inferior goods are goods that people demand less of when their income goes up. This is because inferior goods are considered to be lower-quality goods, and people are willing to spend their money on higher-quality goods when they have more money.
Therefore, the correct answer is A. substitute goods.