It is made of cells. It acts as a barrier. It is made of tissues. It is part of an organism.
I gave my students this multiple choice question: The skin is the largest organ in the human body. Why is skin considered to be an organ?

Only one answer is correct among these 4 choices:
- It is made of cells.
- It acts as a barrier.
- It is made of tissues.
- It is part of an organism.

Could you tell me which one is correct?

It is made of tissues.