After filtration in the nephron, urine primarily contains which of the following?

The primary components found in urine after filtration in the nephron include mineral salts, which are essential for maintaining electrolyte balance and various physiological functions in the body. The filtration process involves the removal of waste products and excess substances from the blood, allowing for the concentration of these components in urine.

Mineral salts, such as sodium, potassium, calcium, and chloride, are regulated by the nephron and are crucial for nerve transmission, muscle contraction, and maintaining fluid balance in the body. After filtration, while the nephron does process other substances such as water and organic molecules, it is specifically the mineral salts that remain significant constituents of urine.

Glucose typically does not remain in the urine in healthy individuals, as it is reabsorbed completely by the nephron. Proteins are generally too large to be filtered effectively and would not be present in urine unless there is a pathological condition. Water, while a major component of urine, does not constitute the primary solute compared to mineral salts. Thus, mineral salts stand out as the correct answer, reflecting the nephron's role in electrolyte homeostasis and waste excretion.