ORS stands for Oral Rehydration Solution, a simple but life-saving mixture of clean water, salt (sodium chloride), and sugar (glucose). It is used to treat dehydration caused by diarrhea, cholera, and other gastrointestinal infections. The glucose enhances sodium absorption in the intestines through the SGLT1 transporter, helping the body retain water and electrolytes. The other options are not the standard medical term.