If a person eats salty food, his or her kidneys respond by excreting excess salt into the

Urine

Explanation:

Excess of salt intake increases the level of salt in our blood. In order to remove excess of salt from blood, the kidneys require to draw excess water through osmosis from the cells.  The functionality of kidney  reduces as it finds it difficult to remove unwanted fluid through blood filtration. A high salt diet disturbs the sodium and potassium balance and hence kidney removes less water there by causing high blood pressure.  

Basically, If a person eats salty food, his or her kidneys respond by excreting excess salt into the URINE

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