If a tube of blood is allowed to stand undisturbed, how many major components will it separate into?

When a tube of blood is allowed to stand undisturbed, it separates into three major components due to the effects of gravity on the cellular and liquid components of the blood. These components consist of the plasma, the buffy coat, and the red blood cells.

Plasma makes up the liquid part of blood, comprising about 55% of its volume, and it contains water, electrolytes, proteins, hormones, and waste products. The buffy coat, which is a thin layer that sits between the plasma and red blood cells, consists of white blood cells and platelets. The red blood cells, which are denser than the other components, settle at the bottom of the tube.

The separation occurs due to the differences in density and size of each component, resulting in a clear stratification when the blood is allowed to sit still. Hence, the correct answer reflects the three distinct components that are visible after the separation process.