Explanation:

- Say’s Law of Market: This principle asserts that supply creates its own demand. It implies that production will inherently generate enough income to purchase what is produced.

- Perfect Flexibility of Wage Rate: This concept suggests that wages adjust freely and instantly to changes in labor market conditions. It helps maintain full employment in the economy.

- Perfect Flexibility of Interest Rate: This idea implies that interest rates readily adjust to changes in savings and investment, facilitating a balance between the two.

- All of these: The classical viewpoint depends on all the above concepts to ensure self-regulating and efficient markets.

Correct Answer: Option 4 - All of these