This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skin lesions and disorders of pigmentation, Subject name: Dental
There is defect in production of melanin in all except- 
Select and explain. 
A. Albinism, B. Vitiligo, C. Piebaldism, D. Melasma
D: Melasma
Answer: D: Melasma 
Explanation: In melasma is a accuired hyperpigmentary disorder affecting predominantly over face. etiology is ultra violet rays. It is also triggered by pregnancy and oral contraceptive pills. All the other given conditions are associated with defects in melanin pproduction IADVL textbook of dermatology, pigmentary disorders,page745