Answer: c. It develops when the concentration of blood sodium falls below a healthy range.
Explanation:
Hyponatremia is a condition in which sodium concentration in serum is decrease below the value of 136 mEq/L. This occurs due to excess of water present in serum in relation to the solute. The common causes of this condition includes diarrhea, liver disease, heart failure, and renal disease.
Nausea, headache, vomiting and confusion are the signs and symptoms of hyponatremia.