The correct series of events that describes the economic history of the Soviet Union in chronological order after Stalin’s death is:
Under Stalin, the economy rapidly industrialized. This continued after his death before stagnating. It began declining under Brezhnev because he focused too much of the economy on the military. When Gorbachev instituted reforms to allow for private industry, the economy collapsed.
This sequence accurately reflects the trajectory of the Soviet economy from Stalin's industrialization policies through the stagnation and decline during Brezhnev's time, ultimately leading to the collapse of the economy following Gorbachev’s reforms.