I believe the correct answer is C. chiaroscuro.
They are known for their masterful use of chiaroscuro, a
technique that uses strong tonal contrasts between light and dark to model
three-dimensional forms. Caravaggio made the chiaroscuro dominant stylistic
element in his art, and his dramatic use of chiaroscuro came to be known as
tenebrism. Zurbaran also used chiaroscuro as dominant technique in which he
excelled, which is why he gained the nickname Spanish Caravaggio.
