What notion was challenged by the work of postwar-era scientists?
There are no answers.
Accuracy is impossible.
Science can explain everything,
Scientific theories reflect reality.

aa dikha du tujhe mera wala dance

c. free trade can lead to low pay for workers in poorer countries.

answer is b.

  it is always the best policy to have good communication and good relations between individuals and, specially, between leaders of the countries. for this purpose, among others, there is a common place, the united nations, where the representants can present his and learn about the other country's policies.