Which of the following is not a disorder of water balance?
◦ hypotonic hydration, in which sodium content is normal but water content is high
◦ excessive hydration due to excess atrial natriuretic peptide (ANP) secretion
◦ excess water in interstitial spaces due to a low level of plasma proteins
◦ edema or tissue swelling, which is usually due to an increased capillary hydrostatic pressure