The correct answer is: very fine, soft hair on the face and arms of people with anorexia nervosa.
Lanugo is usually unpigmented hair that is sometimes found on the body of a fetal or new-borns. Besides that, lanugo can be found in malnourished patients, like those with eating disorders (anorexia nervosa or bulimia nervosa) or in teratomas (congenital tumours).