Answer:
d. there is a technological improvement.
Explanation:
a) replacing production of one good in favor of another will be a move across the PPF
b) abandon inefficient production will bring the production to the PPF from a place below it.
c) has no relationship it will simply put inflationary pressure.
d) the technological improvement will make a better use of the factor thus, increasing productivity and making possible more production with the same amount of materials.
