Here's why:

* Dehydration is the stimulus.

* The body detects this stimulus and sends a chemical signal (likely involving hormones like ADH) to the nephrons in the kidneys.

* The nephrons respond by absorbing more water and excreting more salt, effectively counteracting the initial stimulus of dehydration.

* This action brings the body back to a state of homeostasis, or balance.

Negative feedback is a regulatory mechanism where the body's response to a stimulus counteracts the stimulus itself, bringing the body back to a set point. This is how many physiological systems maintain stability.