What is chiaroscuro?

a. a painting technique that means dark-gray
b. a painting technique that means bold-light
c. a painting technique that means dark-bold
d. a painting technique that means light-dark

D. A painting technique that means light-dark

Explanation:

Chiaroscuro is a style of painting popularized between the fifteenth and seventeenth centuries, just between the height of the Renaissance and the development of the Baroque.

Chiaroscuro  literally means "dark light" .

Through the use of shadows and lights an illusion of depth and volume of the subjects modeled in the work is created. This technique was widely used in religious art.

Leonardo Da Vinci, for example, used this technique  also using another technique called vanished.