What is the primary composition of sweat?

The primary composition of sweat is primarily water and various electrolytes, predominantly salt (sodium chloride), along with small amounts of waste products such as urea and other metabolic wastes. Sweat serves as a means for the body to regulate temperature through evaporative cooling and also to excrete some waste products from the body.

Water constitutes about 99% of sweat, but it is the presence of these electrolytes and small amounts of metabolic byproducts that define the composition. Urea, a product of protein metabolism, is present in sweat in lesser amounts and plays a minor role in the overall function of sweat.

This understanding emphasizes the role of sweat not just in thermoregulation, but also in maintaining the balance of fluids and electrolytes in the body, highlighting the physiological functions behind sweat production and excretion. Other options do not adequately encompass the full range of components typical in sweat, which is why they are not considered correct.