Choice "B" is correct. If the dollar gains in value, net exports will suffer as U.S. goods become more expensive overseas; hence aggregate demand will decrease. The supply of foreign goods domestically should increase as imports become cheaper.
Choice "a" is incorrect. Demand should decrease, not increase.
Choice "c" is incorrect. Irrelevant to the question.
Choice "d" is incorrect. Demand should decrease, not remain the same.
