Answer:
It's the first one (So he can gain wisdom and give advice when needed.)
Explanation:
Because if he doesn't give advice to those in need then they will end up making mistakes that lead up to these memories.
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.
Gregor was quite confused of how he changed in the dream therefore he was heavily affected by it and soon came to past. He felt sad when the raindrops pittered and pattered on the window pane which indeed matched his mood of how he was. But when his mother asked him if he wanted to go somewhere he replied in a forced but uncertain tone. Henceforth he felt partially full because of the meaning of how it had happened.
