What are the hallmark signs of dehydration?

The hallmark signs of dehydration include increased thirst, dry mucous membranes, decreased urinary output, and tachycardia.

When the body becomes dehydrated, it typically reacts by intensifying the sensation of thirst, motivating the individual to consume more fluids to restore balance. Dry mucous membranes are a direct consequence of inadequate fluid levels, resulting in a lack of moisture in areas like the mouth and throat. Decreased urinary output indicates that the body is conserving water due to insufficient hydration, leading to more concentrated urine. Tachycardia, or an increased heart rate, commonly occurs as the body tries to maintain adequate blood flow and blood pressure despite diminished blood volume caused by dehydration.

These signs collectively reflect the body's compensatory mechanisms and the physiological impact of losing moisture. Therefore, the combination of these symptoms makes option B the most accurate description of the hallmark signs of dehydration.