Which type of solution contains dissolved crystals for fluid replacement?

B. Crystalloid solutions are the correct answer because they are defined as solutions that contain small molecules which can easily pass through cell membranes. These solutions typically include water as a solvent along with dissolved electrolytes and other small, low-weight substances, which form a clear solution. When administered for fluid replacement, crystalloid solutions are effective in expanding extracellular fluid volume, making them essential for rehydration and maintaining hemodynamic stability.

Crystalloid solutions can be isotonic, hypotonic, or hypertonic depending on their electrolyte composition relative to the blood plasma. They are commonly used in medical settings, especially to replace fluids that may have been lost due to conditions such as dehydration, surgery, or trauma.

Other types of solutions, such as colloidal solutions, contain larger particles that do not easily dissolve and are used differently, often to expand blood volume in specific situations. Hypertonic solutions have a higher concentration of solutes than blood plasma and are used in particular conditions to shift fluid into the vascular space. Isotonic solutions maintain fluid balance but do not necessarily contain dissolved crystals in the same context as crystalloid solutions.