Atheme is best described as —
a. a moral lesson presented in a work of literature
b. the central idea or insight about life revealed in a literary work
c. the subject of a work of literature
d. a series of related events in a literary work

b. the central idea or insight about life revealed in a literary work

Example:

The theme of The Adventures of Theseus is B: It is as important to be thoughtful as well as brave. 

Theseus was a brave young man called Theseus, who went on a journey to Athens. His mother begged him to travel by sea, not over land it was dangerous travelling over land. He insisted on travelling over land and met several robbers and bandits along the way. He handled each situation he found himself in, along the way, with thought and bravery. As a result, he arrived in Athens unscathed.