Among the artists mentioned, I think that Pablo Picasso showed the quality and development of the post-war period. His work during this period, especially his masterpiece "Guernica," includes the horror and brutality of war, especially in relation to the Spanish Civil War. Picasso's use of abstract and concrete techniques reflects the chaos and confusion experienced during the war. In addition, the discovery of new forms and ideas of art challenged cultural norms, reflecting the spirit of innovation and change that was known after the war.

I agree, Pablo Picasso's work during the post-war period truly showcased the transformative nature of art in that era. "Guernica" is undoubtedly a powerful reflection of the horrors of war, and not just limited to the Spanish Civil War. The painting's abstract and concrete techniques capture the chaos, destruction, and suffering caused by war, making it a timeless symbol of anti-war sentiment.

Furthermore, Picasso's exploration of new artistic forms and ideas challenged traditional norms, which aligns perfectly with the spirit of innovation and change that emerged after World War II. His ability to break away from conventional art styles and push the boundaries of artistic expression paved the way for many subsequent artists to do the same.

Overall, Picasso's contribution to the post-war art world was profound, both in terms of depicting the societal impact of war and inspiring a new wave of artistic experimentation and innovation. His work continues to be celebrated and studied to this day for its historical significance and artistic brilliance.