In mature works of Piet Mondrian he uses red yellow and blue which make up a?

In mature works, Piet Mondrian employs the primary colors red, yellow, and blue, which form the foundation of his abstract compositions. These colors, along with black and white, are used to create a dynamic balance and harmony within his grid-like structures. Mondrian believed that these primary colors represented the pure essence of art, embodying simplicity and clarity. His focus on geometric forms and primary colors aimed to express universal beauty and a sense of order.