Which theme is central to this story from aesop’s fables?

the boy who cried wolf
there was once a young shepherd boy who tended his sheep at the foot of a mountain near a dark forest. it was rather lonely for him all day, so he thought upon a plan by which he could get a little company and some excitement. he rushed down towards the village calling out "wolf, wolf." the villagers came out to meet him, and some of them stopped with him for a considerable time. this the boy so much that a few days afterwards he tried the same trick, and again the villagers came to his . but shortly after this a wolf actually did come out from the forest, and began to worry the sheep, and the boy of course cried out "wolf, wolf," still louder than before. but this time the villagers, who had been fooled twice before, thought the boy was again deceiving them, and nobody stirred to come to his . so the wolf made a good meal of the boy's flock.

a.
the same trick will not always work on the same people.
b.
we cannot always rely on others to us.
c.
it is unwise to trust those who rely on flattery.
d.
a liar will not be believed, even when he speaks the truth.