Georgia O'Keeffe was a 19th-century American modernist painter, who stood out for drawing landscapes, flowers and skyscrapers. O'Keeffe began painting after formal artistic training in the 1910s and she created many paintings during most of her life. However, during the 1970s O'Keeffe lost part of her vision due to macular degeneration, which is an eye-related disease. Due to this, her last painting that was oil in canvas was created in 1972 as the vision loss prevent her from continue painting. So, the correct answer is C. Until the 1970s
