Vitamin B1 is chemically known as Thiamine.
Vitamin B2 is chemically known as Riboflavin.
Vitamin B6 is chemically known as Pyridoxine.
Vitamin C is chemically known as Ascorbic acid.
Therefore, the correct matching is A-III, B-IV, C-I, D-II.
Answer: A-III, B-IV, C-I, D-II