Question: The 1990–91 season was the last season of which top level football league in East Germany?

Context paragraphs:
1990–91 NOFV-Oberliga: The 1990–91 season of the DDR-Oberliga, now renamed NOFV-Oberliga, was the last season of the DDR-Oberliga.  After the season the league was dissolved and the clubs integrated into the German football league system.  Depending on their performance in the 1990–91 season the clubs would join either the Bundesliga, the 2.  Bundesliga, or the Oberliga for the following season.

2015–16 Romanian Superliga (women's football): The 2015–16 season of Romania's top level women's football league was the third under the new name Superliga.  The old name Liga I is now being used for the new second level league.  It is the 26th season of top level football and will decide the Romanian champions and UEFA Women's Champions League participant.

2014–15 Romanian Superliga (women's football): The 2014–15 season of Romania's top level women's football league was the second under the new name Superliga.  The old name Liga I is now being used for the new second level league.  It is the 25th season of top level football and will decide the Romanian champions and UEFA Women's Champions League participant.

Torsten Gütschow: Torsten Gütschow (born 28 July 1962) is a German football manager and former footballer who played as a striker.  He is most associated with Dynamo Dresden, with whom he had two successful spells, playing top level football in East Germany and after reunification.  In between these he played for three other German clubs, and spent six months with Galatasaray of the Turkish Super Lig.  A strong and instinctive goalscorer, Gütschow was top scorer in each of the last three seasons of the DDR-Oberliga, and was the last ever East German Footballer of the Year.  He won three international caps for East Germany, scoring two goals between 1984 and 1989.  Since retiring he has taken up coaching, and has been manager of TuS Heeslingen.

2013–14 Romanian Superliga (women's football): The 2013–14 season of Romania's top level women's football league was the first under the new name Superliga.  The old name Liga I is now being used for the new second level league.  It is the 24th season of top level football and will decide the Romanian champions and UEFA Women's Champions League participant.

1952–53 DDR-Oberliga championship play-off: The championship play-off of the 1952–53 DDR-Oberliga took place on 5 July 1953 at the Walter-Ulbricht-Stadion in East Berlin between Dynamo Dresden and Wismut Aue.  The match decided the winner of the 1952–53 DDR-Oberliga, the 4th season of the DDR-Oberliga, the top level football league in East Germany.  The match was necessary as both teams finished the season level on points.  At the time, the rules stated that if this were to occur, a playoff would be necessary to decide the national champion.  With a 3–2 victory after extra time, Dynamo Dresden secured the championship for their 1st national title.

DDR-Oberliga: The DDR-Oberliga (English:"East German Premier League or GDR-Premier League") was the top level football league in East Germany.

2016–17 Romanian Superliga (women's football): The 2016–17 season of Romania's top level women's football league was the fourth under the new name Superliga.  It is the 27th season of top level football and will decide the Romanian champions and UEFA Women's Champions League participant.

Karsten Härtel: Karsten Härtel (born 4 April 1961) is a former German footballer.  He played as a goalkeeper at club level from the early-1980s to the mid-1990s.  He is best known for playing for Hallescher FC from 1987 to 1989 in the DDR-Oberliga, the top level football league in East Germany.  Following the German reunification, he played for Alemannia Aachen and Bonner SC.

1950–51 DDR-Oberliga championship play-off: The championship play-off of the 1950–51 DDR-Oberliga took place on 20 May 1951 at the Ernst-Thälmann-Stadion in Chemnitz between Chemie Leipzig and Turbine Erfurt.  The match decided the winner of the 1950–51 DDR-Oberliga, the 2nd season of the DDR-Oberliga, the top level football league in East Germany.  The match was necessary as both teams finished the season level on points.  At the time, the rules stated that if this were to occur, a playoff would be necessary to decide the national champion.  With a 2–0 victory, Chemie Leipzig secured the championship for their 1st national title.

Supporting paragraphs: 1990–91 NOFV-Oberliga DDR-Oberliga
Answer: DDR-Oberliga