Answer:
The answers is: B) 5 apples; 2 apples
Step-by-step explanation:
The opportunity cost is how much of one product you are giving up when you decide to take a different product.
In this case, for every pair of shoes an American worker decides to make, he is not growing 5 apples (100 apples / 20 pairs of shoes).
And for every pair of shoes a Canadian worker decides to make, he is not growing 2 apples (20 apples / 10 pairs of shoes).