Approximately how much surface area does this organ cover

Skin is the largest organ and covers a surface area of 20 square feet.

Explanation:

Skin has three layers the epidermis, the dermis and the hypodermis. the epidermis is the outermost layer and provides a water-proof barrier. The dermis contains hair follicles, connective tissue and sweat glands. The hypodermis is the subcutaneous deeper layer made up of connective tissue and fat.

you may having too much sleep.. a good night sleep consists of about 7 hours. more than that could be the reason you're still tired throughout the day.

d, i believe because of it's activity level