This is the most important electrolyte influencing the amount of water that is either retained in blood or eliminated in urine.

Sodium electrolyte

Explanation:

Sodium is a very much essential electrolyte that is required by the human bodies. This directly influences the amount of water present in the human body, including the water that either retains in the blood or are eliminated through the urine. Within the body sodium reacts with water and it helps in maintaining the fluid quantity both inside the cells as well as on the outside of the cells. Consuming lesser amount of sodium helps in the retention of water in the body. Sodium electrolyte is helpful in growing proper body muscles and functioning of the nervous system.

Hence, the correct answer is sodium electrolyte.

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