Foreign exchange is the currency of another country that can be used to purchase goods and services globally. There are various sources of foreign exchange, and the correct answer is exports. Let's understand the different sources of foreign exchange.

Sources of foreign exchange:

1. Imports: Imports are goods and services that a country purchases from other countries. When a country imports, it pays in foreign currency, which increases the supply of foreign exchange.

2. Donations given: Donations given to a country by other countries or international organizations can also be a source of foreign exchange. However, this source is not reliable and depends on the goodwill of other countries.

3. Exports: Exports are goods and services produced in a country and sold to other countries. When a country exports, it receives payment in foreign currency, which increases the supply of foreign exchange.

4. Gifts: Gifts given to a country by other countries or individuals can also be a source of foreign exchange. However, this source is not reliable and depends on the goodwill of donors.

Conclusion:

In conclusion, the correct answer to the question is exports. When a country exports, it earns foreign currency, which increases the supply of foreign exchange. It is important for a country to maintain a positive balance of trade by exporting more than it imports to ensure a steady supply of foreign exchange.