Questions

The error lies in the second part of the sentence. The form V + -ing is called a gerund if it serves as a noun. In the given sentence "to" has been used as a preposition (in a prepositional phrase) and not an infinitive, thus, the gerund form "seeing" is correct. E.G. I look forward to meeting my relatives. Thus, option 2 is correct. Here, 'used to' is used in the present tense to indicate that one has a habit of doing something.

Aldosterone is a key steroid hormone critical for maintaining salt and water balance. It regulates the concentration of minerals, like sodium and potassium, in the fluid outside your cells. When your sodium levels drop, or potassium levels rise, your body signals your adrenal glands to release aldosterone into your blood. Aldosterone signals your kidneys to reabsorb sodium into the blood, and acts on your sweat glands to reduce sodium loss through sweat.