The balance of payments of a country is a systematic record of all import and export transactions of a country during a given period of time, typically a year. It includes both visible transactions (goods) and invisible transactions (services, income, transfers) between residents and non-residents of the country.
The balance of payments provides a comprehensive overview of the economic transactions between a country and the rest of the world. It includes transactions related to trade in goods and services, income flows such as wages and dividends, transfers such as foreign aid and remittances, and capital flows such as investments and loans.
Therefore, the correct answer is "All import and export transactions of a country during a given period of time, normally a year."