A "closed economy" is an economy in which neither exports nor imports take place. In a closed economy, all economic activities take place within the boundaries of the country, and there is no trade with other countries. All the goods and services that are consumed in the economy are produced within the country itself.

The other options mentioned in the question are not necessarily characteristics of a closed economy. The money supply can be fully controlled or deficit financing can take place in both open and closed economies. Similarly, only exports taking place does not necessarily make an economy closed, as imports may still take place.