Mikhail Gorbachev is _______________ with helping to bring about the end of communism in Europe. (achieving, assisted, compute, credited, evaluated, instituted, obtained, primary, residents, site)

Read the following paragraph first.Erich Honecker, the leader of East Germany at that time, predicted in January 1989 that the Berlin Wall would stand for 50 or 100 more years; however, to almost everyone's surprise, the Wall began to fall in November 9th of that year and was demolished within a few days. According to the indications of the given paragraph, make a right order of the following sentences: ①The pressure from the inside of East Germany generated by the nation-wide protest demonstrations in September 1989 was the first driving force behind the fall. ②The last cause was a failure in communication. ③The external pressure, mainly from the Soviet leader Mikhail Gorbachev, also engendered the critical change in East Germany. ④There are three underlying causes that triggered the fall: internal pressure, external pressure and communication failure. A: ④①③② B: ④③①② C: ①③②④ D: ③①②④