The answer is: C. Not to try and fix them all, but also not participate in them
Thoreau just want people to know that evil exist and there we might not be able to eliminate them completely. By knowing this, we can always prepare ourselves to take care of evils when we need but not completely lose our mind over it. Simply by choosing not to participate is often enough because the more people do it, the less evil would exist in this world.
If I recall, I think filthy water that is...
Same-> they had very little food, it was extremly cold in the winter, and thay hade to build everything by themselves.
