Of the four authors that have written books about Hurricane Katrina, the one that is most likely offering an objective account is B: a day-by-day account by a print journalist.
We might think that A is the correct answer because nobody could tell the experience like a person who lived in the place where the hurricane happened. Despite of this fact, he or she will tell his / her own experience and it might not be the experience of others. It will be a subjective account, truthful, but subjective.
On the other hand, a journalist who researched climate facts and consequences of the hurricane could give a more objective account. The journalist would show not one personal experience, but a lot of experiences from different families.