उत्तर : 4. "थियामीन"
व्याख्या :

1. The first vitamin discovered in 1897 was thiamine, also known as vitamin B1.

2. Thiamine was discovered by Dutch physician Christiaan Eijkman.

3. Vitamin B1 helps body cells convert carbohydrates into energy and maintain proper functioning of the heart, muscles and digestive system.