Read these lines: "Tom said to himself that it was not such a hollow world, after all. 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 law stated in the quoted lines is that people want most what

1. The law names one cause and one effect only. 2. The cause is making a thing difficult to attain, and the effect is that a person covets it. 3. Difficult to attain means kept out of easy reach, which is option D. 4. Option A brings in price, which is never part of the rule as stated. 5. Option B says the opposite, since a thing already allowed is easy rather than difficult. 6. Option C swaps difficulty for a warning, and no warning appears in the rule. 7. The rest of the scene supports option D, because the brush is wanted only once it is refused. _Source: Mark Twain, The Adventures of Tom Sawyer (1876), public domain_