What condition arises due to a deficiency of water in the body?

Dehydration is the correct answer because it specifically refers to a state in which the body loses more fluid than it takes in, leading to a deficiency of water. This condition can result from factors such as not drinking enough fluids, excessive sweating, diarrhea, or vomiting, which ultimately disrupts the body's fluid balance.

Understanding dehydration is crucial in sports medicine, as athletes are particularly susceptible to this condition due to the demands of physical activity, which can lead to significant fluid loss. Symptoms of dehydration include thirst, dry mouth, decreased urine output, and in severe cases, confusion or lethargy, all of which can impact athletic performance and overall health.

The other options relate to different health concerns. Heat stroke is a severe condition resulting from prolonged exposure to high temperatures, leading to a failure of the body's temperature regulation, rather than a lack of water alone. Malnutrition refers to an overall lack of necessary nutrients in the diet, which can include calories, carbohydrates, fats, vitamins, or minerals, but is not solely linked to fluid intake. Hypotension, or low blood pressure, can occur due to dehydration, but it is not a condition caused by the deficiency of water alone; it can have multiple causes and is characterized by low blood pressure readings