Which solution is primarily composed of salt and water?

Normal saline is a solution that is primarily composed of salt (sodium chloride) and water. It has a concentration of 0.9% sodium chloride, which is isotonic with human blood. This makes it a standard fluid for various medical purposes, including intravenous (IV) hydration, as it helps to maintain fluid balance in the body without causing cellular disruption.

Ringer's lactate also contains salt but includes additional electrolytes like potassium, calcium, and lactate, making it a more complex solution. Dextrose is a type of sugar solution, often used to provide calories and fluids but lacks a significant concentration of salt. Hypertonic saline contains a higher concentration of salt than normal saline, which can be used for specific medical scenarios but is not primarily composed of just salt and water.

Therefore, normal saline stands out as the standard solution that is specifically and primarily made up of salt and water, making it the correct choice in this context.