Answer: A closed system, because energy can enter or leave the container, but the water molecules cannot
Step-by-step explanation:
According to question, the system given is a closed system.This is because energy is transferred from the burner to glass flask and from the glass flask to the water (matter).
But no water molecule is coming outside the flask instead of that they are getting condensed on the inside surface of the glass flask which means that matter is not allowed to move beyond the boundaries of the system.
Where as in open system both matter and energy are allowed to move beyond the boundaries of the system.
In an isolated system both energy and matter are not allowed to move beyond the boundaries of the system.