Answer:
a. has shifted right, but her opportunity costs of making pies are unchanged.
Explanation:
As we know that Greta curve should be shifted to righward as she can generated more and more units for both the goods so here the c and d option would be remooved. The option A and optoin B are considering the opportunity cost so here we can see that
10 ÷8 = 5 ÷ 4
5 ÷ 4 = 5 ÷ 4
As it can been seen that the opportunity cost remains the same
Therefore the option A is selected