Explanation:

- Option 1: Perfect complements

- Goods consumed together. Think of left and right shoes.

- Indifference curve is L-shaped or right-angled.

- The correct answer: Right-angled indifference curve shows perfect complements.

- Option 2: Perfect substitutes

- Goods easily replaceable with each other. Imagine tea and coffee for some.

- Indifference curve is a straight line.

- Option 3: Inferior goods

- As income rises, demand for these goods falls.

- No specific shape for indifference curves.

- Option 4: Giffen goods

- A type of inferior good where demand increases as price increases.

- Different concept from indifference curves.