Concept:Countries trade internationally because no country can produce every good it needs due to differences in natural conditions.
Explanation:Differences in climate affect which crops and products a country can produce easily.
Differences in natural resources mean some countries have minerals and raw materials that others lack.
These differences create the necessity for exchanging goods with other nations.
Trade barriers do not explain the need for trade; they actually restrict it.
Technological differences are not the primary reason for the basic need to trade.
Hence, the requirement for international trade is best explained by climatic and natural resource variations.
Answer:A. I and II only