One among the following options is not correct

Explanation

This Economics question is asking which option among the given options is not correct. The options are presented in a list format.

Option A states that any point inside the production possibility curve indicates unemployment or underemployment. This is a correct statement because the production possibility curve represents the maximum output that can be produced using the available resources. Any point inside the curve indicates that the resources are not fully utilized, which can be due to unemployment or underemployment.

Option B states that increases in the price of a commodity leads to a fall in the demand for its substitute. This is a correct statement because when the price of a commodity increases, consumers tend to switch to its substitutes. This results in a decrease in the demand for the commodity.

Option C states that the fixing of price above the equilibrium price level leads to a surplus of the commodity. This is a correct statement because when the price is fixed above the equilibrium price level, the quantity supplied exceeds the quantity demanded, resulting in a surplus.

Option D is the correct answer because it states that an increase in both market supply and market demand may not result in a change in equilibrium price and quantity. This statement is not correct because an increase in both market supply and market demand will result in a shift in the equilibrium quantity and price. The new equilibrium point will be where the new supply and demand curves intersect.

In summary, the correct answer to this question is option D. To further understand these concepts, students can read more about demand and supply, equilibrium, and production possibility curve in their Economics textbooks.