Given a scientific question, generate a correct answer to it.

Example Input: Many adults and some children suffer from a deficiency of lactase. these individuals are said to be lactose intolerant because they cannot digest the lactose found in what?
Example Output: milk

Example Input: The urea cycle, a set of biochemical reactions that produces urea from ammonium ions to prevent toxicity, occurs to some extent in the kidney, but primarily in what organ?
Example Output: liver

Example Input: Which group of metals in the periodic table include elements such as sodium and potassium?
Example Output:
alkali metals