Which of the following increases body osmolarity?

Body osmolarity refers to the concentration of solutes in the blood and other body fluids. An increase in osmolarity typically indicates a higher concentration of solutes per volume of water. In this context, elevated blood glucose levels lead to an increase in osmolarity because glucose is a solute. When blood glucose levels rise, especially in conditions such as hyperglycemia, the concentration of glucose in the bloodstream increases, thus raising the overall osmolarity.

On the other hand, hypotonic saline and free water in a feeding tube would contribute to lower body osmolarity as they introduce more water than solute, diluting the existing solute concentration. Isotonic saline, while maintaining osmotic balance, has an equal concentration of solutes and water, meaning it does not increase osmolarity. Therefore, elevated blood glucose levels stand out as the factor that significantly increases body osmolarity.