That answer is because of pre-history if the question asks why it is valuable it is because of rather how long it has existed and what time remnant it existed in.<span />
The answer is "d. <span>(1) values; (2) depth".
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<span>Cross-hatching provides an illusion of various "values", while impasto provides an illusion of "depth".
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Cross-hatching refers to a technique which is used to make a sense of thickness or density by covering lines, and impasto is a strategy used to make a sense of depth through thickly connected paint, regularly so one can see the brush strokes. An artist may choose cross-hatching over impasto to make different qualities or degrees of gentility and darkness.And may choose impasto over cross-hatching to accentuate depth or dimension to a work of art.
Answer:
Encryption maybe so only certain individuals can decrypt it and finding out that my work has been used without my knowledge would make legal process the next line of action.