Explanation

Niacin or nicotinamide (nicotinic acid) is also called anti-pellagra vitamin. Its deficiency causes pellagra in which skin becomes scaly and pigmented. Deficiency of pyridoxine (Vit-$B_{6}$) causes anaemia, neuritic pain, convulsions, skin lesions, etc. Deficiency of folic acid causes megaloblastic or macrocytic anaemia, while deficiency of biotin (vitamin-$B_{4}$ or vitamin-H) causes dermatitis and anorexia.