According to Christopher L.C.E. Witcombe in his essay "The Roots of Modernism," the modern era in art spans approximately from 1860 to 1970. How does he commonly characterize modernism?
Explanation
Option A states that modernism is the art produced during the modern era, while option C describes it as the philosophy underpinning modern art. Witcombe defines modernism as including both these aspects, making option D the correct choice.