Question:
Who was the head of Poland in Sep, 1989?

Context:
 Tadeusz Mazowiecki is the head of the government of Poland from Aug, 1989 to Jan, 1991. 
 Jarosław Kaczyński is the head of the government of Poland from Jul, 2006 to Nov, 2007. 
 Hanna Suchocka is the head of the government of Poland from Jul, 1992 to Oct, 1993. 
 Mateusz Morawiecki is the head of the government of Poland from Dec, 2017 to Dec, 2022. 
 Marek Belka is the head of the government of Poland from May, 2004 to Oct, 2005. 
 Ewa Kopacz is the head of the government of Poland from Sep, 2014 to Nov, 2015. 
 Jerzy Buzek is the head of the government of Poland from Oct, 1997 to Oct, 2001. 
 Jan Krzysztof Bielecki is the head of the government of Poland from Jan, 1991 to Dec, 1991. 
 Donald Tusk is the head of the government of Poland from Nov, 2007 to Sep, 2014. 
 Włodzimierz Cimoszewicz is the head of the government of Poland from Feb, 1996 to Oct, 1997. 
 Beata Szydło is the head of the government of Poland from Nov, 2015 to Dec, 2017. 
 Józef Oleksy is the head of the government of Poland from Mar, 1995 to Feb, 1996. 
 Jan Olszewski is the head of the government of Poland from Dec, 1991 to Jun, 1992. 
 Waldemar Pawlak is the head of the government of Poland from Oct, 1993 to Mar, 1995. 
 Leszek Miller is the head of the government of Poland from Oct, 2001 to May, 2004. 
 Kazimierz Marcinkiewicz is the head of the government of Poland from Oct, 2005 to Jul, 2006.

Answer:
Tadeusz Mazowiecki