Which is necessary for a society to be considered a civilization?
choose all answers that are correct.
a. literature
b. division of labor
c. a hierarchy of priests
d. more food than is needed for survival
e. organized schools

The correct answer in my opinion would be that D is the most important factor here. But this question is quite tricky.

We can surely say for example that literature, organized schools and a hierarchy of priests are not something that constitute a civilization. Organized schools appeared to late, not every civilization had literature and having only a hierachy of priests is not enough to say you have a civilizaton.

Labor has been divided in pre-civilization hunter-gatherer societies as well. 

For that reason I'd say the correct answer is D - more food than is needed for survival. Having this, the people in a certain group can focus on other things.