What percentage range represents the adult body's water composition?

• A. 50-60%
• B. 40-50%
• C. 60-70%
• D. 70-80%

Answer: (A)

Total body water is about half of body weight in adults, with some variation based on body composition and age. Water is distributed between intracellular fluid (inside cells) and extracellular fluid (outside cells), and lean tissue contains more water than fat tissue. Because men typically have more lean mass, their total body water is often around the higher end (near 60%), while women and older adults, who have more body fat, tend to be closer to about 50–55%. This natural variation is why a practical range used is 50–60% of body weight. The other ranges would suggest less typical hydration levels for most adults (40–50%) or unusually high water content (60–70% or more), which doesn’t align with normal physiology for the average adult.