Final answer:
Piet Mondrian was a founder of the De Stijl movement, known for its simplicity, abstraction, and geometric compositions.
Step-by-step explanation:
Piet Mondrian was a founder of the De Stijl movement. De Stijl was a Dutch art movement that emphasized simplicity, abstraction, and geometric compositions. Mondrian's famous paintings, characterized by grids of horizontal and vertical lines with primary colors and black and white, are iconic examples of the style.
Learn more about Piet Mondrian and the De Stijl movement