Final answer:
c) Sodium is the element that maintains fluid and acid-base balance, with its main dietary source being salt. It is crucial for blood volume and pH regulation. Other electrolytes like potassium also contribute to fluid and electrolyte balance in the body.
Step-by-step explanation:
The element that maintains fluid and acid-base balance and whose main dietary source is salt is sodium. Sodium, along with potassium and chlorine, is primarily involved in acid-base balance and the osmotic control of water metabolism. The main sources of sodium in our diet include table salt and processed foods. Potassium is also important for maintaining fluid and electrolyte balance, particularly for the proper functioning of the heart and nerves, as well as water balance and pH level. It can be found in many fruits and vegetables. Similarly, electrolytes like magnesium, calcium, and potassium are important for metabolic regulation and can impact blood pressure by reducing sodium retention.