Step 1: Concept Clarification:
The objective is to identify the option that impedes international trade, as opposed to promoting it, according to the provided text.
Step 3: Detailed Analysis:
The text indicates that international trade relies on "specialization in production" (aligning with option A), requires "mutual benefit" (option B), and is supported by "well-developed transportation" (related to option D). It also notes the connection to "foreign policy of nations". While foreign policy is linked to trade, disagreements in foreign policy would obstruct, not foster, trade. Cooperation, not conflict, underpins thriving trade.
Step 4: Conclusive Answer:
Disagreements in the foreign policies of trading nations constitute an obstacle to, rather than a basis for, international trade.