In his essay “The Roots of Modernism,” Christopher L.C.E. Witcombe defines the modern period in the history of art as the time from roughly 1860 to 1970. How does he say modernism is typically defined ?

A. Modernism is the art produced during the modern period.
B. Modernism is the historical period which followed the modern period.
C. Modernism is the philosophy of modern art.
D. Both A and C