Question:
Who was the head of Germany in Mar, 1973?

Context:
 Konrad Adenauer is the head of the government of Germany from Sep, 1949 to Oct, 1963. 
 Walter Scheel is the head of the government of Germany from May, 1974 to May, 1974. 
 Kurt Georg Kiesinger is the head of the government of Germany from Dec, 1966 to Oct, 1969. 
 Angela Merkel is the head of the government of Germany from Nov, 2005 to Dec, 2021. 
 Willy Brandt is the head of the government of Germany from Oct, 1969 to May, 1974. 
 Ludwig Erhard is the head of the government of Germany from Oct, 1963 to Nov, 1966. 
 Gerhard Schröder is the head of the government of Germany from Oct, 1998 to Oct, 2005. 
 Helmut Kohl is the head of the government of Germany from Oct, 1982 to Oct, 1998. 
 Helmut Schmidt is the head of the government of Germany from May, 1974 to Oct, 1982. 
 Olaf Scholz is the head of the government of Germany from Dec, 2021 to Dec, 2022.

Answer:
Willy Brandt