Step 1: Understanding foreign exchange reserves.
Foreign exchange reserves increase primarily through export trade, as the country earns foreign currency from the goods and services it exports.
Step 2: Analyzing the options.
- (A) By Import Trade: Incorrect. Import trade results in an outflow of domestic currency, which reduces foreign exchange reserves.
- (B) By Export Trade: Correct. Export trade brings in foreign currency, thus increasing foreign exchange reserves.
- (C) By National Level Trade: Incorrect. While national level trade involves both imports and exports, it is the export side that increases reserves.
- (D) By Domestic Trade: Incorrect. Domestic trade does not involve foreign currency and does not impact foreign exchange reserves.
Step 3: Conclusion.
Foreign exchange reserves increase through export trade, making option (B) the correct answer.
Final Answer:} By Export Trade.