To show depth, artists also make images behind the original image . darker
lighter
bluer
thicker

Darker

Explanation:

I believe it is darker because having a darker image behind the original image would make it look as if the original image has a shadow. Shadows make the artwork have more depth and makes the artwork more lifelike.

the answer is counterpoint.

counterpoint definition: "the art or technique of playing a melody or melodies in conjunction with another, according to fixed rules."

counterpoint is present in a lot of baroque music- such as bach (notably his wtc prelude and fugues) and scarlatti, but can also be found in music by mozart, beethoven. it can even be found in music as modern as john williams!