Question:
Which position did Thomas S. Gates, Jr. hold in Mar, 1960?

Context:
 Thomas S. Gates, Jr. holds the position of United States Secretary of Defense from Dec, 1959 to Jan, 1961. 
 Thomas S. Gates, Jr. holds the position of United States Secretary of the Navy from Apr, 1957 to Jun, 1959. 
 Thomas S. Gates, Jr. holds the position of United States Deputy Secretary of Defense from Jun, 1959 to Dec, 1959. 
 Thomas S. Gates, Jr. holds the position of United States Ambassador to China from Apr, 1976 to May, 1977. 
 Thomas S. Gates, Jr. holds the position of Under Secretary of the Navy from Oct, 1953 to Apr, 1957.

Answer:
United States Secretary of Defense