Which one is not a precondition of law of demand? A Price of substitutesB Income of the consumerC WagesD Population

To identify which choice is not a precondition of the law of demand, let's analyze each option in terms of how they relate to demand:

1. Price of Substitutes: This is a relevant factor as the demand for a good can increase if the price of its substitute rises. Therefore, it is a precondition of the law of demand.

2. Income of the Consumer: Consumer income affects their purchasing power. Higher income generally leads to higher demand for normal goods, hence it is a precondition of the law of demand.

3. Wages: Wages are a component of income. While they affect overall income and purchasing ability, they are not explicitly mentioned as a standalone precondition for the law of demand.

4. Population: The number of consumers in a market can influence overall demand. A larger population typically leads to increased demand, making it relevant to the law of demand.

Conclusion

Wages (C) stand out as not being a direct precondition of the law of demand when considered separately from income, which incorporates wages. Thus, the answer is C: Wages.