Which of the following best defines Gross Domestic Product (GDP)?

The correct choice defines Gross Domestic Product (GDP) as the total monetary value of all final goods and services produced within a country during a specific period, usually a year. This definition captures the essence of GDP, which is fundamentally a measure of economic activity. It includes all finished products and services that are produced and sold within the country's borders, reflecting the overall production capability and economic health of the economy.

This measurement is a key indicator used by economists to gauge the size and performance of an economy, indicating growth or contraction. It excludes intermediate goods to avoid double counting, focusing only on those products that have completed the production process.

The other options don’t align with the definition of GDP accurately. For example, total income received by residents is more aligned with Gross National Income (GNI), while investments are part of GDP calculations but do not encompass the entire definition. National debt is a different economic concept entirely and does not represent production or economic output.