Explanation:

- Exports

- The correct source of foreign exchange.

- When a country sells goods and services to other countries, foreign buyers pay in foreign currency. This influx of currency increases the foreign exchange reserves of the exporting country.

- Imports

- This does not generate foreign exchange.

- Instead, it involves the outflow of domestic currency to pay for goods and services bought from abroad.

- Gifts

- Generally, gifts do not serve as a major source of foreign exchange.

- They're usually one-way transactions without a reciprocal increase in foreign currency.

- Donations given

- Similar to gifts, donations given away from a country involve the outflow rather than the inflow of currency.