Largest organ in the human body.

**The reasoning** When we talk about the "largest organ," we mean by *surface area* and *weight*. Your skin covers your entire body — from head to toe — measuring about **1.5 to 2 square meters** in an adult and weighing roughly **4 to 5 kg**. That's bigger than any internal organ! The skin is also classified as an organ because it has multiple tissue types working together (epidermis, dermis, subcutaneous layer) to perform vital functions: protection, temperature regulation, sensation, and vitamin D synthesis. **Why the wrong options tempt you** - **Heart** — You might pick this because it's the most "important" organ you hear about. But importance ≠ size. - **Liver** — It's the largest *internal* organ (about 1.5 kg), so this tricks students who forget skin counts as an organ. - **Lungs** — They feel big when you breathe deeply, but combined they weigh only about 1 kg and have less surface area than skin. **Quick takeaway** The skin is your body's protective wrapper — largest by area and weight, covering roughly 2 square meters of you!