Final answer:
Rosa Bonheur utilized chiaroscuro to imply roundness and bulk in her painting Harvest Season, using contrasts between light and dark to create the illusion of three-dimensional forms.
Step-by-step explanation:
Rosa Bonheur used chiaroscuro in several places in her painting Harvest Season to suggest their roundness and bulk. Chiaroscuro is an artistic technique where the artist uses strong contrasts between light and dark to give the illusion of volume in modelling three-dimensional objects and figures. This technique emphasizes the roundness and bulk of the subjects, as seen in the way Bonheur painted the animals in her work, giving a realistic representation of their form and mass.