Question:
Who was the head of state of German Democratic Republic in Aug, 1990?

Context:
 Manfred Gerlach is the head of the state of German Democratic Republic from Dec, 1989 to Apr, 1990. 
 Sabine Bergmann-Pohl is the head of the state of German Democratic Republic from Apr, 1990 to Oct, 1990. 
 Walter Ulbricht is the head of the state of German Democratic Republic from Sep, 1960 to Aug, 1973. 
 Willi Stoph is the head of the state of German Democratic Republic from Oct, 1973 to Oct, 1976. 
 Egon Krenz is the head of the state of German Democratic Republic from Oct, 1989 to Dec, 1989. 
 Wilhelm Pieck is the head of the state of German Democratic Republic from Oct, 1949 to Sep, 1960. 
 Erich Honecker is the head of the state of German Democratic Republic from Oct, 1976 to Oct, 1989.

Answer:
Sabine Bergmann-Pohl