Skin Is Sometimes Referred to as the Largest Organ of the Body.Why

Skin is sometimes referred to as the largest organ of the body.Why is skin considered to be an organ and not a tissue or some other structure?

A) Skin consists of multiple cell types functioning as a single integrated unit.
B) Skin consists of multiple tissue types that cooperate to perform a specific task.
C) Skin is a vital component of multiple organ systems.
D) Skin consists of a single cell type.