With Respect to Air,water,and Material Resources,which of the Following Is

Multiple Choice

With respect to air,water,and material resources,which of the following is true?

A) a leaf is a closed system.
B) a leaf is an open system.
C) a leaf is an open system in terms of air,but closed in terms of material resources.
D) a leaf is an open system in terms of water,but closed in terms of energy resources.
E) a leaf does not represent a system.