In the art piece described, the trait that most directly communicates the likeness of the individual in an artistic way would be:
the soft use of shadows and highlights to create the features.
This technique helps to define the contours of the face, giving depth and dimension that can resemble the individual more closely. The other options, while they may contribute to the overall aesthetic, do not specifically relate to capturing the likeness of the person as effectively as the manipulation of light and shadow does.