To calculate the opportunity cost of producing one unit of Good B in terms of Good A, we need to determine how many units of Good A are being sacrificed when we produce Good B.
Given:
- The country can produce a maximum of 20,000 units of Good A or 5,000 units of Good B.
First, we need to determine how many units of Good A are produced per unit of Good B. The opportunity cost can be calculated using the following formula:
\[ \text{Opportunity Cost of 1 unit of Good B} = \frac{\text{Total units of Good A}}{\text{Total units of Good B}} \]
Substituting in the values:
\[ \text{Opportunity Cost of 1 unit of Good B} = \frac{20,000 \text{ units of Good A}}{5,000 \text{ units of Good B}} = 4 \text{ units of Good A} \]
Thus, the opportunity cost of producing one unit of Good B is 4 units of Good A.
Therefore, the correct response is:
4 units of Good A.