Which film marked a significant evolution of American cinema through its tackling of complex themes and racial issues?

"Broken Blossoms," directed by D.W. Griffith in 1919, is recognized for its exploration of complex themes, particularly in relation to race and societal issues. The film tells the poignant story of the relationship between a Chinese immigrant and a young white girl in a deteriorating and prejudiced environment, which highlights the harsh realities of racism and violence prevalent in that era.

Griffith’s approach in "Broken Blossoms" was innovative for its time; it used visual storytelling to convey deep emotional and societal messages rather than relying solely on dialogue. This film is often considered a significant turning point in American cinema because it attempted to address controversial subjects that had been largely neglected in film prior to this point. By dealing with such delicate topics, "Broken Blossoms" pushed the boundaries of what films could address, setting a precedent for future filmmakers to explore complex narratives regarding race and human relationships.

The other films listed either do not delve as deeply into these themes or lack the same level of historical significance in the context of cinema's evolution concerning racial issues. Thus, "Broken Blossoms" stands out as a crucial work in the history of American filmmaking.