An investigation of the transition to democracy in Eastern Europe would likely help to prove true the following statement:
Religion could be practiced more freely in most Eastern European countries.
The other options are generally inaccurate or too broad, as the transition to democracy and the adoption of free markets faced various challenges and outcomes across different countries in the region. The statement about democracy thriving in all countries would also not be accurate, considering that some nations experienced setbacks in their democratic processes. Lastly, the claim about the Soviet Union remaining the dominant force is outdated, as the fall of the Soviet Union marked a significant change in the political landscape of Eastern Europe.