How do artists use gradation in their work? what does adding value gradation do?

Gradation of color and value can also be useful when painting other subjects. In a still life, for example, you might use a gradation in the background from left to right and from top to bottom. Please give me the brailiest answer?

:) Hoped this helped <3

answer; i believe the correct answer is in new york,in subway stations,public murals and night clubs;

the answer is false i think