Answer: Option (a) is the correct answer.
Explanation:
According to thermodynamics, a closed system is defined as the system in which there will be no exchange of matter takes place but there will be exchange of energy between the system and surrounding.
On the other hand, an open system is defined as the system in which there will be exchange of both matter and energy takes place between system and surrounding.
Hence, we can conclude that out of the given options accurate descriptions of closed and open thermodynamic processes is that open processes are 'flow through' processes.