What was a common thread in the fall of communist regimes throughout eastern europe
a. a decline in education and health care
b. poor economies and demands for more rights
c. a lack of strong leaders in communist governments
d. support for military alliance with the united states

The most common thread in the fall of communist regimes throughout Eastern Europe was: B. Poor economies and demands for more rights 

By not giving any Economic freedom to their people, the communist countries killed the desire to thrive and compete that became the basis of gathering wealth, leaving the country with a bunch of people that could only wait for the government to tell them what to do.

Not only that, the Communist's citizen own absolutely nothing. All of the things that exist in that country was owned by the government.