I think maybe C? Not sure though, so don't take my word as gospel :)
Answer:
Georgia O'Keeffe. Trees in Autumn, 1920-1921. Oil on canvas, 25 3/16 x 20 3/16 inches. Georgia O'Keeffe Museum (Santa Fe), Gift of The Burnett Foundation.
Explanation:
Usually a government site or anything that ends in .org or .gov
