Question:
Who was the head of Soviet Union in Mar, 1959?

Context:
 Nikolai Bulganin is the head of the government of Soviet Union from Feb, 1955 to Mar, 1958. 
 Nikolai Tikhonov is the head of the government of Soviet Union from Oct, 1980 to Sep, 1985. 
 Ivan Silayev is the head of the government of Soviet Union from Sep, 1991 to Dec, 1991. 
 Alexei Kosygin is the head of the government of Soviet Union from Oct, 1964 to Oct, 1980. 
 Valentin Pavlov is the head of the government of Soviet Union from Jan, 1991 to Aug, 1991. 
 Nikolai Ryzhkov is the head of the government of Soviet Union from Sep, 1985 to Jan, 1991. 
 Georgy Malenkov is the head of the government of Soviet Union from Mar, 1953 to Feb, 1955. 
 Alexei Rykov is the head of the government of Soviet Union from Feb, 1924 to Dec, 1930. 
 Vyacheslav Molotov is the head of the government of Soviet Union from Dec, 1930 to May, 1941. 
 Joseph Stalin is the head of the government of Soviet Union from May, 1941 to Mar, 1953. 
 Nikita Khrushchev is the head of the government of Soviet Union from Mar, 1958 to Oct, 1964. 
 Vladimir Lenin is the head of the government of Soviet Union from Jul, 1923 to Jan, 1924.

Answer:
Nikita Khrushchev