The correct answer is: Skin.
The skin is the largest organ in the human body, weighing about 10 pounds and covering an area of about 20 square feet. It is made up of three layers: the epidermis, the dermis, and the hypodermis. The epidermis is the outermost layer and is made up of dead cells that are constantly being shed. The dermis is the middle layer and is made up of connective tissue, blood vessels, nerves, and hair follicles. The hypodermis is the innermost layer and is made up of fat cells.
The skin has many important functions, including protecting the body from the environment, regulating body temperature, and producing vitamin D. It is also a sensory organ that helps us to feel touch, pressure, pain, and temperature.
The heart is the second largest organ in the human body. It is a muscular organ that pumps blood throughout the body. The brain is the third largest organ in the human body. It is the control center of the body and is responsible for all of our thoughts, feelings, and movements. The liver is the fourth largest organ in the human body. It is responsible for many important functions, including filtering toxins from the blood, producing bile, and storing energy.