Answer: Open system
Explanation:
There are three types of systems:
Open System: A system where mater and energy both can pass across the boundary. Example: Tea kept in a cup
Closed system: A system where mater can not be exchanged but energy can be exchanged. Example: Tea kept in a kettle
Isolated System: A system where neither mater nor energy both can be exchanged. Example: Tea kept in a thermos
