One of the effects of lead poisoning is an inflammation of the optic nerve, which casuese those who have it to see bright haloes around light sources. In aorder to produce the striking yellow effects in his "Sunflowers" paintins, Van Gogh used Naples yellow, a pigment containing lead. Since in his later paintings, van gogh painted bright haloes around hte stars and sun, it is likeluy that he was suffering from lead poisoning caused by ingesting the pigments he used....I understand why the right answer is A. But I can't disprove why the correct answer also can't be D. I felt like by assuming D, it eliminated any other alternative possibility that the OTHER element may have CAUSED Van gogh to see bright haloes. Can someone help??!!