Final answer:
Jackson Pollock was the prominent innovator of Abstract Expressionism who studied with Thomas Hart Benton and David Siqueiros, contributing greatly to the movement with his distinctive drip painting techniques.
Step-by-step explanation:
The leading innovator of Abstract Expressionism who studied with both Thomas Hart Benton and David Siqueiros was Jackson Pollock. He was taught by Thomas Hart Benton when he moved to New York, and his work ultimately contributed to the start of the Abstract Expressionist movement. Despite beginning with regional and representational art under Benton's influence, Pollock's rebellion against these ideas fostered his development into a central figure in Abstract Expressionism. Moreover, Pollock was exposed to the work of Mexican muralist David Siqueiros, which also influenced his innovative artistry and techniques.
In the art world of the 1940s in New York City, Abstract Expressionism became a dominant force. This modernist movement had absorbed and reinterpreted elements from various art styles and movements—including Cubism, Surrealism, and Fauvism—thanks to great teachers from Europe who had recently immigrated to America. Pollock's unique style, often characterized by his famous 'drip paintings,' was one of the results of this rich melting pot of artistic influences.