Final answer:
a. Sodium.
Sodium is the essential mineral necessary for the regulation of blood and body fluids. It helps maintain fluid balance and is required in significant amounts daily.
Step-by-step explanation:
The mineral necessary for the regulation of blood and body fluids is sodium. Sodium is one of the major minerals needed in the body each day in amounts larger than 100 milligrams. It plays a crucial role in maintaining the proper balance of fluids in and around your cells, which is essential for the normal functioning of muscles and nerves. Mineral sources like the common table salt are primary sources of sodium, along with other processed foods.