The Truman Doctrine, also known as the policy of containment, was A, the informal declaration of the Cold War. The Marshall Plan came latter and was aimed at getting European countries on our (US) side by finical means.
Coordinating written communication between separate cities and colonies
Answer: B sounds like the most reasonable answer
Explanation:
Social Darwinism has been used to justify imperialism, racism, eugenics and social inequality at various times over the past century and a half.