Which answer is right?

In shifting to a defense policy based upon the concept of "flexible response," president kennedy was indicating that he had grave doubts about thevalue of which previous defense policy? a massive retaliationb collective securityc containmentd air power

When conducting research for forming a hypothesis, which practice should historians follow?

Iwill arward ! , i if po≅ pr, uo≅ ur, prove: ∠o ≅ ∠r. fill in the blanks: draw segment ≅ uo ≅ po≅ △oup ≅ △