The correct answer is A. Skin
Step-by-step explanation:
In biology and related fields, an organ refers to structures composed of tissues that have a similar or same function. This includes organs such as kidneys, heart, lungs, among others. In the case of skin, this is considered an organ because the cells and tissue that composed skin serve to same purposes that include protecting the body from pathogens, regulating temperature and collecting stimulus related to sensations.
Moreover, the skin is the largest organ in the body because this can be found along all the body acting as an outer covering, while other organs are limited to one location, for example, the heart is only found in the chest, while the skin is the outer covering of the inner structures and tissues.