3-5 days is how long you can go without water
The answer would be the last option which is:
protecting the body
excreting wastes
regulating temperatures
generating vitamins
This includes the skin and its extremities acting to shield the body from different sorts of harm, for example, loss of water or scraped area from outside. The framework has numerous parts in homeostasis. All body frameworks work in an interconnected way to keep up the inside conditions fundamental to the capacity of the body, the skin has a vital activity of securing the body and goes about as the body's first line of protection against contamination, temperature change, and different difficulties to homeostasis.
The reason people cry are for two reasons; One Reflex: the tears are cause by a reflex, from irritants such as wind, smoke, or onions. They are released to flush out these irritants and protect the eye. Emotional: Humans shed tears in response to a range of emotions. These tears contain a higher level of stress hormones than other types of tears.
-Hope this helps-