According to the direct instruction, what color of paint did cennini recommend be used as an underlayer when painting faces?
a. white
b. red
c. green
d. rose

The color green is used as an under layer when painting faces.

Explanation:

Terra Verte is the designation applied to a set of pigments that owe their color to green clay minerals such as celadonite, glauconite and chlorite.

In the Middle Ages it was widely used in tempera painting, especially in a layer underlying the carnation layer. Cennino Cennini describes this use as follows: 'pick up a little green soil and a little lead white, well mixed; apply two layers under the face, under the hands, under the feet and under the carnation areas'; When applying the pink colored layers, 'keep in mind that in wood painting more layers have to be applied than in mural painting; but not many more, so that some of the green that is already under the carnation areas is still visible »