What is dehydration?

Dehydration is best defined as a condition that occurs when the body loses more fluids than it takes in, which aligns perfectly with the correct answer. When the body does not receive sufficient water or loses excessive amounts of fluids through sweat, urine, or other means, it can lead to a deficit of necessary fluids, affecting various bodily functions.

The body relies on a balance of fluids to maintain blood volume, regulate temperature, and support cellular processes. When this balance is disrupted due to inadequate fluid intake or excessive losses, it can lead to dehydration, with symptoms that may include thirst, dry mouth, fatigue, dizziness, and in severe cases, even complications involving vital organs.

The other options do not accurately describe dehydration; for example, fluid retention refers to a different condition where the body retains excess fluid, which is the opposite of dehydration. A stable state of fluid levels would indicate a healthy hydration status, contradicting the concept of dehydration. Excessive water intake, while potentially leading to its own issues like water intoxication, does not describe a deficit of fluids, which is the hallmark of dehydration. Thus, the definition provided in the correct answer captures the essence of what dehydration truly is.