What is the Staffel B that has Hallescher Fc Chemie as Staffel C?
CREATE TABLE "1971_1984" (
  "season" text,
  "staffel_a" text,
  "staffel_b" text,
  "staffel_c" text,
  "staffel_d" text,
  "staffel_e" text
);
SELECT "staffel_b" FROM "1971_1984" WHERE "staffel_c"='hallescher fc chemie';