Whilst all the answers given here are correct in some way, the correct one is still A, preventing a war in Vietnam. The 60s were a hippy era, the pacifist movement against wars. And since the war in Vietnam lasted for 20 years, it is obvious that that is the thing which colored their lives black and something they stood against the most.
Answer:
Ernest Shackleton's failed quest to reach the South Pole is still a management tutorial in how to face repeated crises.
His project is a painting i think
Your answer is A) Humble
Hope this helps. Have a nice day/weekend.