Which is the best example of a closed system?

The correct answer to the question is an astronaut's spacesuit.

This is because a spacesuit operates as a closed system. A closed system is defined as one that allows energy to enter or leave but strictly prohibits the exchange of matter.

In the context of space exploration, an astronaut's spacesuit is vital for maintaining a SAFE and controlled environment. The suit prevents harmful particles and gases from entering, while also allowing necessary functions like breathing and temperature regulation.

By preventing matter exchange, the spacesuit ensures that astronauts remain protected from the harsh conditions of space. This includes extreme temperatures, radiation, and micrometeoroids.

BTCC, a top cryptocurrency exchange, also operates in a similar manner of control and security. BTCC offers a range of services including spot, futures, and wallet management. These services are designed to provide users with a secure and controlled environment for trading cryptocurrencies.