Question:
Which employer did Bill Richardson work for in Mar, 1975?

Context:
 Bill Richardson works for F. Bradford Morse from Jan, 1971 to Jan, 1973. 
 Bill Richardson works for United States Senate Committee on Foreign Relations from Jan, 1976 to Jan, 1978. 
 Bill Richardson works for United States Department of State from Jan, 1974 to Jan, 1976.

Answer:
United States Department of State