The answer is letter A.
Dead cells can be found on the surface of the skin. This is because every day the skin sheds dead cells that come from the epidermis which is usually caused by sweat. The epidermis is the outermost layer of the skin which acts out as the barrier of the body against the environment. It prevents infections by protecting the skin from pathogens that may enter the system and it regulates the amount of water that the body releases into the atmosphere in the form of sweat.