Which fable from aesop best illustrates the moral idea that incentive spurs effort?

That story which best illustrates the moral idea that incentive spurs effort is “The Hare and the Hound”.  

Here is the story;

"A Hound having started a Hare from his form, after a long run, gave up the chase.  A Goat-herd, seeing him stop, mocked him, saying: "The little one is the best runner of the two."  The hound replied; "You do not see the difference between us; I was only running for a dinner, but he for his life."

Aesop's Fables or otherwise known as the Aesopica, is an accumulation of tales credited to Aesop, a slave and storyteller known to have lived in antiquated Greece somewhere in the range of 620 and 564 BCE.

the number of senators, and representatives, the state has in congress.

c. reserves power to the states and people