Quais foram os principais aspectos que contribuíram para o declínio do sistema socialista no leste europeu ?

The main reasons for the 'falling' of the socialistic countries in Europe in about the same time was both, the similar circumstances, and a chain reaction. All of the socialist countries were in dire economic state, they were in big debt, bad economic planing, poverty, growing nationalism. All of these contributed that those countries fall apart, and when the process started with the first country getting out of it, the rest followed, and the central government couldn't control and stop the process.

Ascenario that doesnt  include any modern objects like electricity

The answer is d) rift