7. How did the Truman Doctrine and the Marshall Plan promote the policy of containment?

both strategies went hand in hand and anticipated a slow and cautious process of undermining Communist regimes from within. Immediate results were not expected.

Explanation: Containment had quite different form in different stages. 1950s containment was not so sophisticated as the one in 1960s or 1970s. Undermining of Communist regime became almost scientific discipline, immigrants from Communist regimes were used frequently.

d. promised it other land

i believe your answer is d)