Final answer:
Plasma is the liquid portion of blood, comprising about 55 percent of its volume and composed mostly of water, proteins, and various dissolved substances. It is essential for the transportation of cells, nutrients, and hormones, as well as for maintaining homeostasis within the body.
Step-by-step explanation:
The best description of plasma is that it is the liquid portion of blood containing water, ions, and proteins. Plasma is a critical component of blood, consisting of about 55 percent of its volume and is composed mainly of water—about 92 percent. It plays a role in carrying essential components, such as proteins, glucose, mineral ions, hormones, carbon dioxide, and other substances.
Contrary to options a, c, and d, plasma is not a cellular component, a type of white blood cell, or a clotting factor, although it does contain clotting factors. The primary cells in plasma are red blood cells, which carry oxygen, white blood cells, which defend the body against infections, and platelets, which are essential for blood clotting. Because of its composition, plasma also has an important role in maintaining the pH balance, temperature regulation, and osmotic pressure in the body.
In summary, blood plasma is instrumental in the regulation of body functions, transportation of nutrients and waste, and distribution of hormones, aside from containing components for blood clotting.