Answer:
4 units of good A for Nation X and 1/2 unit of good A for Nation Y
Explanation:
In an economic system where there are two or more goods to be produced, the concept of opportunity cost steps in. Opportunity cost is when a good is chosen to be produced at the expense of other goods due to limited resources. Therefore, the opportunity cost per unit of commodity B is estimated as 4 units and 0.5 units of commodity A for Nations X and Y respectively.