Answer:
A. The harder something is to have, the more likely it is that people will want it.
Tom had discovered the great law of human action. What was it?
In Chapter Two of the Adventures of Tom Sawyer, Tom is forced to whitewash a fence. The fence is thirty yards long and made of boards nine feet high. Since it is a Saturday, all the other boys would be going off to have fun. Tom is smarter than the other body and manages to get them to do his work or him by pretending that whitewashing a fence is not really work but pleasure. He soon has the boys asking him to let them share in his pretended enjoyment. But he refuses at first on the grounds they not only do the whole job but actually pay him for the privilege with marbles, toys, and all sorts of whatnots.
"He had discovered a great law of human action, without knowing it namely, that in order to make a man or a boy covet a thing, it is only necessary to make the thing difficult to attain."
The narrator goes on to explain that work is something that person is obliged to do, while play is something that a person is not obliged to do. Proof of this assertion is the fact that a number of boys get pleasure out of whitewashing 270 square feet of board fence. They actually apply three coasts of whitewash, so the total area painted would amount to a little over 700 square feet. Tom's Aunt Polly is amazed when she comes out to inspect the job,
"When she found the entire fence whitewashed, and not only whitewashed but elaborately coated and recoated, and even a streak added to the ground, her astonishment was almost unspeakable."
This is perhaps the best-known episode in all of Mark Twain's writings. Most editions of the Adventures of Tom Sawyer contain at least one color picture or sketch of a small barefoot boy painting a fence with a big brush. It seems symbolic of a small-town boyhood in American of the nineteenth century.