Hymans and Stafford (1995) Present a Model That Illustrates How

Hymans and Stafford (1995) present a model that illustrates how, under free trade, economic growth in a poor country can cause a decline in a rich country's welfare because:

A) the poor and rich countries PPF curves and relative prices become increasingly similar.
B) the poor and rich countries PPF curves and relative prices become increasingly dissimilar.
C) the poor and rich countries compete for similar resources causing input prices to increase.
D) the poor and rich countries actually increase their trade when the terms of trade in the rich country improve.