Dehydration is defined as

• A. a temporary fluctuation in body weight
• B. a serious reduction in the body's water content
• C. an increase in thirst without dehydration
• D. an overhydration state

Answer: (B)

Dehydration means the body has a serious shortage of water, reducing its total body water to a level that impairs normal function. Water is essential for maintaining blood volume, electrolyte balance, temperature control, and cellular processes, so when water loss exceeds intake, these systems can’t work properly. That’s why dehydration is a deficit state rather than just a minor weight change. The other statements don’t define dehydration: a temporary fluctuation in body weight can happen with normal fluid shifts, thirst alone can occur without a dangerous deficit, and overhydration is the opposite condition, where too much water dilutes body fluids.