Question:
Which employer did Helmuth Nyborg work for in Nov, 1990?

Context:
 Helmuth Nyborg works for University of Washington from Jan, 1990 to Jan, 1991. 
 Helmuth Nyborg works for University of Oxford from Jan, 1979 to Jan, 1980. 
 Helmuth Nyborg works for University of California, Berkeley from Jan, 2000 to Jan, 2001. 
 Helmuth Nyborg works for Aarhus University from Jan, 1968 to Jan, 2007. 
 Helmuth Nyborg works for The Rockefeller University from Jan, 1989 to Jan, 1990.

Answer:
University of Washington