You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: CHEMISTRY 
Clue: She had high school chemistry with Peter Jacobson, whom she married in 1978 & later helped create "The Nanny"
fran drescher

Category: HERE'S TO WATER 
Clue: This city's water treatment plant, the world's largest, lies on a 61-acre peninsula that extends into Lake Michigan
chicago

Category: THEY FOUND MORE THAN ONE ELEMENT 
Clue: Klaproth, who found cerium, also found this element that's last on the alphabetical list

zirconium