Answer is b. Thiamine
Vitamins are essential nutrients which are crucial for maintaining optimal health. Vitamin B-complex is a water soluble vitamins which includes thiamine (B1), niacin (B3) riboflavin (B2), folate and iron. These are added during enrichment process of foods like cereal grains and breads, as well as other foods such as meat, poultry, eggs, fish milk, legumes, etc.