The hormone ADH (Antidiuretic Hormone) triggers the kidneys to produce more concentrated urine and reduce water loss. It increases reabsorption of water in the kidneys, especially when the body is dehydrated. Other hormones like calcitonin, oxytocin, and PTH have distinct functions unrelated to water regulation. ;
The hormone responsible for triggering the kidneys to form more concentrated urine and prevent excess water loss is ADH (Antidiuretic Hormone). It increases water reabsorption in the kidneys when the body is dehydrated. Therefore, the correct answer is C. ADH.
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