Hair on end appearance in seen in-

Ans. is 'a' i.e., Thalassemia * Hair on end appearance can be seen in the diploic space of the skull and has the appearance of long, thin vertical striations. This appearance is caused by alternating thickened trabeculae and radiolucent marrow hyperplasia* Hair on end appearance is characteristically and most commonly seen in thalassemia because marrow hyperplasia is more marked in this than other anemia.* Sickle cell anemia is the 2nd most common cause (after thalassemia).Other causes* Hereditary spherocytosis* G6PD or Pyruvate kinase deficiency* Severe iron deficiency anemia* Neoplastic: - Hemangioma, neuroblastic metastasis* Cyanotic heart disease