Final answer:
Marie Laurencin's artwork is categorized as Cubist because of the incorporation of geometric shapes, which is a defining characteristic of Cubism.
Step-by-step explanation:
One reason that Marie Laurencin's artwork is considered Cubist, despite her use of pastel and curvilinear aesthetics, is its incorporation of geometric shapes. While Cubism is known for its geometric abstraction, Cubist artists deconstructed and reformed shapes to offer a three-dimensional perspective using geometric forms positioned in non-illusionistic areas. Laurencin, associated with prominent Cubists like Metzinger and Braque, adopted this approach in her own distinctive style.