Answer:
The correct answer is option d.
Step-by-step explanation:
An inferior good is that kind of good which has a negative relationship with income. This means that an increase in income would cause their demand to decrease and vice versa.
We can say that unlike normal goods, it shows negative income elasticity. When consumer's income decreases the inferior goods become an affordable substitute, so their demand increases.
A basic example of inferior goods is public transport. When the income of the consumer is low he commutes through public transport buses, trains, etc. But as his income increases, he will instead prefer to travel in his own car.