Answer:
The Iran-Contra scandal
Step-by-step explanation:
George H.W. Bush's presidential term was from 1989-1993
The reunification of Germany took place in 1990, under the Bush Administration
The fall of the Soviet Union was in 1991, under the Bush Administration
The Gulf War was from 1990-1991, under the Bush Administration
The Iran-Contra scandal was from 1985-1987, under the Reagan Administration