The third blank is limited I believe and the first is veto?? And the second is override.
Answer:
For half a century, memories of the Holocaust limited anti-Semitism on the Continent. That period has ended—the recent fatal attacks in Paris and Copenhagen
Explanation:
The factors that made it difficult for Eastern Europe to improve its water quality were outdated sewer systems, raw water quality, worn-out water utilities and unskilled employees. So we can say that four options given in the question fits the bill perfectly. These basic infrastructural reasons were responsible for being a hurdle towards improving the water quality. <span />
